RD Sharma Solutions Class 12 Mathematics Chapter 19 MCQ
RD Sharma Solutions Class 12 Mathematics Chapter 19 MCQ
Updated on 24 Jan 2022, 02:20 PM IST
The class 12 RD Sharma chapter 19 exercise MCQ solution deals with the chapter of definite integrals which is a sub part of the indefinite integrals chapter, The Definite integral is defined to be the exact limit and summation that we looked at in the past section to find the net area between a function and the X-axis . The RD Sharma class 12th exercise MCQ gives us the brief practice of the entire chapter and makes us go through all the concepts one by one to revise each and every topic of the chapter thoroughly.
Answer: 2 Hint: Using $\int x \; d x \text { and } \frac{d}{d x}(\tan x)$ Given: $\int_{0}^{\pi} \frac{1}{1+\sin x}$ Explanation: Let $\begin{aligned} &I=\int_{0}^{\pi} \frac{1}{1+\sin x} \\\\ &=\int_{0}^{\pi} \frac{1}{1+\frac{2 \tan {x} / 2}{1+\tan^ {2} x / 2}} d x \end{aligned}$ $\begin{aligned} &=\int_{0}^{\pi} \frac{1+\tan ^{2 } \frac{x}{2}}{1+\tan ^{2} x / 2+2 \tan x / 2} d x \\\\ &=\int \frac{\sec ^{2 } \frac {x}{2}}{\tan ^{2} x / 2+2 \tan \frac{x}{2}+1} d x \end{aligned}$
$\begin{aligned} &\text { Put } 2 \tan \frac{x}{2}=t \\\\ &\sec ^{2} x / 2 \cdot 1 / 2 d x=d t \\\\ &\sec ^{2} x / 2 d x=2 d t \end{aligned}$ When $x=0$ then $t= 0$ When $x=\pi$ then $t= \infty$ $\begin{aligned} &=\int_{0}^{\infty} \frac{2 d t}{t^{2}+2 t+1} \\\\ &=\int_{0}^{\infty} \frac{1}{(t+1)^{2}} d t \end{aligned}$ $\begin{aligned} &=\int_{0}^{\infty}(t+1)^{-2} d t \\\\ &=\left[\frac{(t+1)^{2}}{-2+1}\right]_{9}^{\infty} \end{aligned}$ $\begin{aligned} &=-2\left[\frac{1}{(t+1)}\right]_{9}^{\infty} \\\\ &=-2(0-1) \\\\ &=2 \end{aligned}$
Answer: $\frac{\pi }{4}$ Given: $\int_{0}^{\frac{\pi}{2}} \frac{\sqrt{\cos x}}{\sqrt{\cos x}+\sqrt{\sin x}} d x$ Hint: using $\int_{0}^{a} f(x) d x=\int_{0}^{a} f(a-x) d x$ Explanation: Let $I=\int_{0}^{\frac{\pi}{2}} \frac{\sqrt{\cos x}}{\sqrt{\cos x}+\sqrt{\sin x}} d x \ldots(i)$ $I=\int_{0}^{\frac{\pi}{2}} \frac{\sqrt{\cos \left(\frac{\pi}{2}-x\right)}}{\sqrt{\cos \left(\frac{\pi}{2}-x\right)}+\sqrt{\sin \left(\frac{\pi}{2}-x\right)}} d x, \quad\left[\therefore \int_{0}^{a} f(x) d x=\int_{0}^{a} f(a-x) d x\right]$$=\int_{0}^{\frac{\pi}{2}} \frac{\sqrt{\sin x}}{\sqrt{\sin x}+\sqrt{\cos x}} d x \ldots(i i)$ Adding (i) and (ii) $\begin{aligned} &2 I=\int_{0}^{\frac{\pi}{2}} \frac{\sqrt{\cos x}+\sqrt{\sin x}}{\sqrt{\sin x}+\sqrt{\cos x}} d x \\\\ &=\int_{0}^{\frac{\pi}{2}} 1 d x \\\\ &2 I=[x]_{0}^{\frac{\pi}{2}} \\\\ &2 I=\left[\frac{\pi}{2}-0\right] \end{aligned}$ $\begin{aligned} &2 I=\frac{\pi}{2} \\\\ &I=\frac{\pi}{4} \end{aligned}$
Answer: 2 Given: $\int_{0}^{\frac{\pi^{2}}{4}} \frac{\sin \sqrt{x}}{\sqrt{x}} d x$ Hint: Using $\int \sin x\; dx$ Explanation: Let $\begin{aligned} &I=\int_{0}^{\frac{\pi^{2}}{4}} \frac{\sin \sqrt{x}}{\sqrt{x}} d x \\\\ &\text { Put } \sqrt{x}=t \\\\ &\frac{1}{2 \sqrt{x}} d x=d t \\\\ &\frac{1}{\sqrt{x}} d x=2 d t \end{aligned}$ $\begin{aligned} &=\int_{0}^{\frac{\pi}{2}} \sin t \cdot 2 t\; d t \\\\ &=2\left[\frac{-\cos t}{1}\right]_{0}^{\frac{\pi}{2}} \end{aligned}$ $\begin{aligned} &=2\left[-\cos \frac{\pi}{2}+\cos 0\right] \\\\ &=2[0+1] \\\\ &=2 \end{aligned}$
Answer: $\frac{2}{\sqrt{3}} \tan ^{-1}\left(\frac{1}{\sqrt{3}}\right)$ Given: $\int_{0}^{\frac{\pi}{2}} \frac{1}{2+\cos x} d x$ Hint: Using$\int \frac{1}{1+x^{2}} d x$
Explanation: Let $I=\int_{0}^{\frac{\pi}{2}} \frac{1}{2+\cos x} d x$ Put $\begin{aligned} &\cos x=\frac{1-\tan ^{2} x / 2}{1+\tan ^{2} x / 2} \\\\ &=\int_{0}^{\frac{\pi}{2}} \frac{1}{2+\frac{1-\tan ^{2} x / 2}{1+\tan ^{2} x / 2}} d x \end{aligned}$ $=\int_{0}^{\frac{\pi}{2}} \frac{1+\tan ^{2} x / 2}{2\left(1+\tan ^{2} x / 2\right)+1-\tan ^{2} x / 2} d x$ $=\int_{0}^{\frac{\pi}{2}} \frac{\sec ^{2 } x/ 2}{3+\tan ^{2} x / 2} d x$ $\begin{aligned} &\text { Put } \tan ^{x} /_{2}=t \\\\ &\sec ^{2} x / 2 \cdot 1 / 2 d x=d t \\\\ &\sec ^{2} x /{ }_{2} d x=2 d t \end{aligned}$ When $x=0$ then $t= 0$ When $x=\frac{\pi }{2}$ then $t=1$ $\begin{aligned} &=\int_{0}^{1} \frac{2 d t}{t^{2}+(\sqrt{3})^{2}} \\\\ &=2\left[\frac{1}{\sqrt{3}} \tan ^{-1}\left(\frac{t}{\sqrt{3}}\right)\right]_{0}^{1} \\\\ &=\frac{2}{\sqrt{3}}\left[\tan ^{-1}\left(\frac{1}{\sqrt{3}}\right)-\tan ^{-1}(0)\right] \end{aligned}$ $\begin{aligned} &=\frac{2}{\sqrt{3}}\left[\tan ^{-1}\left(\frac{1}{\sqrt{3}}\right)-0\right] \\\\ &=\frac{2}{\sqrt{3}} \tan ^{-1}\left(\frac{1}{\sqrt{3}}\right) \end{aligned}$
Answer: $\frac{\pi}{2}-1$ Given: $\int_{0}^{1} \sqrt{\frac{1-x}{1+x}} d x$ Hint: Explanation: Let $\begin{aligned} &I=\int_{0}^{1} \sqrt{\frac{1-x}{1+x}} d x \\\\ &=\int_{0}^{1} \sqrt{\frac{1-x}{1+x} \times \frac{1-x}{1-x}} d x \end{aligned}$ $\begin{aligned} &=\int_{0}^{1} \sqrt{\frac{(1-x)^{2}}{1-x^{2}}} d x \\\\ &=\int_{0}^{1} \frac{1-x}{\sqrt{1-x^{2}}} d x \end{aligned}$ $\begin{aligned} &=\int_{0}^{1} \frac{1}{\sqrt{1-x^{2}}} d x-\int_{0}^{1} x\left(1-x^{2}\right)^{-1 / 2} d x \\\\ &=\int_{0}^{1} \frac{1}{\sqrt{1-x^{2}}} d x+\int_{0}^{1}\left(1-x^{2}\right)^{-1 / 2}(-2 x) d x \end{aligned}$ $\begin{aligned} &=\left[\sin ^{-1} x\right]_{0}^{1}+\frac{1}{2}\left[\frac{\left(1-x^{2}\right)^{1 / 2}}{1 / 2}\right]_{0}^{1} \\\\ &=\left[\sin ^{-1}(1)-\sin ^{-1}(0)\right]+\frac{1}{2}\left[0-\frac{1}{1 / 2}\right] \end{aligned}$ $\begin{aligned} &=\left(\frac{\pi}{2}-0\right)+\frac{1}{2}(-2) \\\\ &=\frac{\pi}{2}-1 \end{aligned}$
Answer: $\frac{\pi}{\sqrt{a^{2}-b^{2}}}$ Given: $\int_{0}^{\pi} \frac{1}{a+b \cos x} d x$ Hint: Using$\int \frac{1}{1+x^{2}} d x$ Explanation: Let $\begin{aligned} &I=\int_{0}^{\pi} \frac{1}{a+b \cos x} d x \\\\ &\cos x=\frac{1-\tan ^{2} x / 2}{1+\tan ^{2} x / 2} \end{aligned}$ $\begin{aligned} &=\int_{0}^{\pi} \frac{1}{a+b\left(\frac{1-\tan ^{2} x / 2}{1+\tan ^{2} x / 2}\right)} d x \\\\ &=\int_{0}^{\pi} \frac{1+\tan ^{2} x / 2}{2 a+a \tan ^{2} x / 2+b-b \tan ^{2} x / 2} d x \end{aligned}$ $\begin{aligned} &=\int_{0}^{\pi} \frac{\sec ^{2 } \frac{x}{2}}{(a-b) \tan ^{2} x / 2+(a+b)} d x \\\\ &\text { Put } \tan {x} /_{2}=t \\\\ &\sec ^{2} x / 2 \cdot{ }^{1} /{ }_{2} d x=d t \\\\ &\sec ^{2} x /{2} d x=2 d t \end{aligned}$ $=\int_{0}^{\infty} \frac{2 d t}{(a-b) t^{2}+(a+b)}$ $=\frac{2}{(a-b)} \int_{0}^{\infty} \frac{d t}{t^{2}+\left(\sqrt{\frac{a+b}{a-b}}\right)^{2}}$ $=\frac{2}{a-b}\left\{\tan ^{-1}\left[t \sqrt{\frac{a-b}{a+b}}\right]\right\}_{0}^{\infty} \times \frac{1}{\sqrt{\frac{a+b}{a-b}}}$ $\begin{aligned} &=\frac{2}{a-b} \frac{\sqrt{a-b}}{\sqrt{a+b}}\left(\tan ^{-1} \infty-\tan ^{-1} 0\right) \\\\ &=\frac{2}{\sqrt{(a+b)(a-b)}} \cdot\left(\frac{\pi}{2}\right) \\\\ &=\frac{\pi}{\sqrt{a^{2}-b^{2}}} \end{aligned}$
Answer: $\frac{\pi }{12}$ Given: $\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \frac{1}{1+\sqrt{\cot x}} d x$ Hint: Using$\int_{a}^{b} f(x) d x=\int_{a}^{b} f(a+b-x) d x$
Explanation: Let $\begin{aligned} &I=\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \frac{1}{1+\sqrt{\cot x}} d x \\\\ &I=\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \frac{1}{1+\sqrt{\frac{\cos x}{\sin x}}} d x, \quad\left[\therefore \cot x=\frac{\cos x}{\sin x}\right] \end{aligned}$ $=\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \frac{\sqrt{\sin x}}{\sqrt{\sin x}+\sqrt{\cos x}} d x \ldots(i)$ We have a property that $\int_{a}^{b} f(x) d x=\int_{a}^{b} f(a+b-x) d x$ Using this, we get $=\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \frac{\sqrt{\cos \left(\frac{\pi}{3}+\frac{\pi}{6}-x\right)}}{\sqrt{\cos \left(\frac{\pi}{3}+\frac{\pi}{6}-x\right)}+\sqrt{\sin \left(\frac{\pi}{3}+\frac{\pi}{6}-x\right)}} d x$ $=\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \frac{\sqrt{\cos x}}{\sqrt{\cos x}+\sqrt{\sin x}} d x,\left[\therefore \sin \left(\frac{\pi}{2}-x\right)=\cos x, \quad \cos \left(\frac{\pi}{2}-x\right)=\sin x\right]$ $I=\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \frac{\sqrt{\cos x}}{\sqrt{\cos x}+\sqrt{\sin x}} d x \ldots(i i)$ Adding (i) and (ii) $\begin{aligned} &2 I=\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \frac{\sqrt{\sin x}+\sqrt{\cos x}}{\sqrt{\sin x}+\sqrt{\cos x}} d x \\\\ &=\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} 1 d x \end{aligned}$ $\begin{aligned} &I=\frac{1}{2}[x]_{\frac{\pi}{6}}^{\frac{\pi}{3}} \\\\ &I=\frac{1}{2}\left[\frac{\pi}{3}-\frac{\pi}{6}\right] \end{aligned}$ $\begin{aligned} &I=\frac{1}{2}\left[\frac{2 \pi-2 \pi}{6}\right] \\\\ &I=\frac{1}{2} \times \frac{\pi}{6} \\\\ &=\frac{\pi}{12} \end{aligned}$
Answer: $\frac{\pi}{60}$ Given: $\int_{0}^{\infty} \frac{x^{2}}{\left(x^{2}+a^{2}\right)\left(x^{2}+b^{2}\right)\left(x^{2}+c^{2}\right)} d x=\frac{\pi}{2(a+b)(b+c)(c+a)}$ Hint: Using given condition find a,b,c.
Explanation: Given that $\int_{0}^{\infty} \frac{x^{2}}{\left(x^{2}+a^{2}\right)\left(x^{2}+b^{2}\right)\left(x^{2}+c^{2}\right)} d x=\frac{\pi}{2(a+b)(b+c)(c+a)} \ldots(i)$ We have to evaluate $\int_{0}^{\infty} \frac{d x}{\left(x^{2}+4\right)\left(x^{2}+9\right)}$ Let $I=\int_{0}^{\infty} \frac{d x}{\left(x^{2}+4\right)\left(x^{2}+9\right)}$ Multiply and divide by $x^{2}$ $I=\int_{0}^{\infty} \frac{x^{2} d x}{\left(x^{2}+4\right)\left(x^{2}+9\right)\left(x^{2}+0\right)}$ On comparing with equ (i) We get $\begin{aligned} &a^{2}=4 ; b^{2}=9 ; c^{2}=0 \\\\ &a=2 ; b=3 ; c=0 \end{aligned}$ To given $\int_{0}^{\infty} \frac{x^{2}}{\left(x^{2}+a^{2}\right)\left(x^{2}+b^{2}\right)\left(x^{2}+c^{2}\right)} d x=\frac{\pi}{2(a+b)(b+c)(c+a)}$ $\int_{0}^{\infty} \frac{x^{2}}{\left(x^{2}+a^{2}\right)\left(x^{2}+b^{2}\right)\left(x^{2}+c^{2}\right)} d x=\frac{\pi}{2(2+3)(3+0)(0+2)}$ $=\frac{\pi}{2 \times 5 \times 3 \times 2}$ $=\frac{\pi}{60}$
Answer: 1 Given: $\int_{1}^{\theta} \frac{\log x}{x} d x$ Hint: Using by parts. Explanation: Let $\begin{aligned} I &=\int_{1}^{e} \log x d x \\\\ &=\left[\log x \int 1 d x-\int \frac{d}{d x}(\log x)-\int d x\right]_{1}^{e} \end{aligned}$ $\begin{aligned} &=\left[x \log x-\int \frac{1}{x} \cdot x d x\right]_{1}^{e} \\\\ &=[x \log x-x]_{1}^{e} \end{aligned}$
Answer: 2 Given: $\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} \sin |x| d x$ Hint: You must know about $\left | x \right |$ function and $\int \sin x\; dx$
Explanation: Let $I=\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} \sin |x| d x$ We know that $\begin{aligned} &|x|=\left\{\begin{aligned} x, & x \geq 0 \\ -x, & x<0 \end{aligned}\right. \\\\ &I=\int_{-\frac{\pi}{2}}^{0} \sin (-x) d x+\int_{0}^{\frac{\pi}{2}} \sin x \; d x \end{aligned}$ $\begin{aligned} &I=-\int_{-\frac{\pi}{2}}^{0} \sin x \: d x+\int_{0}^{\frac{\pi}{2}} \sin x \; d x \\\\ &=-[-\cos x]_{-\frac{\pi}{2}}^{0}+[-\cos x]_{0}^{\frac{\pi}{2}} \end{aligned}$ $\begin{aligned} &=[\cos x]_{-\frac{\pi}{2}}^{0}-[\cos x]_{0}^{\frac{\pi}{2}} \\\\ &=\cos (0)-\cos \left(-\frac{\pi}{2}\right)-\cos \frac{\pi}{2}+\cos (0) \\\\ &=1-0-0+1 \\\\ &=2 \end{aligned}$
Answer: $\frac{\pi}{4}$ Given: $\int_{0}^{\frac{\pi}{2}} \frac{1}{1+\tan x} d x$ Hint: using$\int_{0}^{a} f(x) d x=\int_{0}^{a} f(a-x) d x$
Explanation: Let $\begin{aligned} &I=\int_{0}^{\frac{\pi}{2}} \frac{1}{1+\tan x} d x \\\\ &I=\int_{0}^{\frac{\pi}{2}} \frac{1}{1+\frac{\sin x}{\cos x}} d x \end{aligned}$ $\begin{aligned} &I=\int_{0}^{\frac{\pi}{2}} \frac{\cos x}{\cos x+\sin x} d x \ldots(i) \\\\ &I=\int_{0}^{\frac{\pi}{2}} \frac{\cos \left(\frac{\pi}{2}-2\right)}{\cos \left(\frac{\pi}{2}-2\right)+\sin \left(\frac{\pi}{2}-2\right)} d x \end{aligned}$ $I=\int_{0}^{\frac{\pi}{2}} \frac{\sin x}{\sin x+\cos x} d x \ldots(i i)$ Adding (i) and (ii) $\begin{aligned} &2 I=\int_{0}^{\frac{\pi}{2}} \frac{\sin x+\cos x}{\sin x+\cos x} d x \\\\ &2 I=\int_{0}^{\frac{\pi}{2}} 1 d x \end{aligned}$ $\begin{aligned} &I=\frac{1}{2}[x]_{0}^{\frac{\pi}{2}} \\\\ &I=\frac{1}{2}\left[\frac{\pi}{2}-0\right] \\\\ &=\frac{\pi}{4} \end{aligned}$
Answer: $e-1$ Given: $\int_{0}^{\frac{\pi}{2}} \cos x \cdot e^{\sin x} d x$ Hint: You must know about $\frac{d}{d x}(\sin x)$ and $\int e^{t} d t$
Explanation: Let $I=\int_{0}^{\frac{\pi}{2}} \cos x \cdot e^{\sin x} d x$ Put $\begin{aligned} &\sin x=t \\\\ &\cos x \; d x=d t \end{aligned}$ When$x=0$ then $t= 0$ When $x=\frac{\pi }{2}$ then $t=1$ $\begin{aligned} &=\int_{0}^{1} e^{t} d x \\\\ &=\left[e^{t}\right]_{0}^{1} \\\\ &=e^{1}-e^{0} \\\\ &=e-1 \end{aligned}$
Answer: 0 Given: $\int_{0}^{1} f(x) d x=1 ; \int_{0}^{1} x f(x) d x=a ; \int_{0}^{1} 2 x^{2} f(x) d x=a^{2}$ Hint: To solve this equation, we have to integrate differentially.
Explanation: $\begin{aligned} &\int_{0}^{1} f(x) d x=1 \ldots(i) \\\\ &\int_{0}^{1} x f(x) d x=a \ldots(i i) \\\\ &\int_{0}^{1} 2 x^{2} f(x) d x=a^{2} \ldots(i i i) \end{aligned}$ $\begin{aligned} &I=\int_{0}^{1}(a-x)^{2} f(x) d x \\\\ &I=\int_{0}^{1}\left(a^{2}+x^{2}-2 a x\right) f(x) d x \end{aligned}$ $\begin{aligned} &I=\int_{0}^{1} a^{2} f(x) d x+\int_{0}^{1} x^{2} f(x) d x-\int_{0}^{1} 2 a x f(x) d x \\\\ &I=a^{2} \int_{0}^{1} f(x) d x+\int_{0}^{1} x^{2} f(x) d x-2 a \int_{0}^{1} x f(x) d x \end{aligned}$ $\begin{aligned} &I=a^{2}+a^{2}-2(a)(a) \\\\ &I=2 a^{2}-2 a^{2} \\\\ &I=0 \end{aligned}$
Answer: 0 Given: $\int_{-\pi}^{\pi} \sin ^{3} x \cos ^{2} x \; d x$ Hint: This equation is solve by $\int_{-a}^{a} f(x) d x$
Explanation: $\begin{aligned} &\int_{-a}^{a} f(x) d x \\\\ &f(-x)=\sin ^{3}(-x) \cdot \cos ^{2}(-x) \end{aligned}$ $\begin{aligned} &=-(\sin x)^{3} \cdot \cos ^{2} x \\\\ &=-\sin ^{3} x \cdot \cos ^{2} x \\\\ &=-f(x) \end{aligned}$ f(x) is odd function. $\int_{-\pi}^{\pi} \sin ^{3} x \cos ^{2} x \; d x=0$
Answer: $10\left(\frac{\pi}{2}\right)^{9}$ Hint: To solve this equation we convert sin into cos. Given: $I_{10}=\int_{0}^{\frac{\pi}{2}} x^{10} \sin x \; d x$ Solution: $\begin{aligned} &I_{10}=\int_{0}^{\frac{\pi}{2}} x^{10} \sin x\; d x \\\\ &=-x^{10} \cdot \cos x-\int_{0}^{\frac{\pi}{2}} 10 x^{9} \cdot \cos x \; d x \end{aligned}$ $\begin{aligned} &=0-10 \int_{0}^{\frac{\pi}{2}} x^{9} \cdot \cos x \; d x \\\\ &=10\left[x^{9} \sin x-9 \int_{0}^{\frac{\pi}{2}} x^{8} \sin x \; d x\right]_{0}^{\frac{\pi}{2}} \end{aligned}$ $\begin{aligned} &=10\left(\frac{\pi}{2}\right)^{9}-90 \int_{0}^{\frac{\pi}{2}} x^{8} \sin x \; d x \\\\ &=10\left(\frac{\pi}{2}\right)^{9}-90 I_{8} \\\\ &=10\left(\frac{\pi}{2}\right)^{9} \end{aligned}$
Answer: $\frac{1}{2756}$ Hint: Integrate then use limits Given: $\int_{0}^{1} \frac{x}{(1-x)^{54}} d x$ Solution: $\begin{aligned} &I=\int_{0}^{1} \frac{x}{(1-x)^{54}} d x \\\\ &I=\int_{0}^{1} \frac{x}{(x-1)^{54}} \quad\left[\mathrm{Q}(x-y)^{2}=(y-x)^{2}\right] \end{aligned}$ $\begin{aligned} &=\int_{0}^{1} \frac{x+1-1}{(x-1)^{54}} d x \\\\ &=\int_{0}^{1} \frac{(x-1)}{(x-1)^{54}} d x+\int_{0}^{1} \frac{1}{(x-1)^{54}} d x \end{aligned}$ $\begin{aligned} &=\int_{0}^{1}(x-1)^{-53} d x+\int_{0}^{1}(x-1)^{-54} d x \\\\ &=\left[-\frac{(x-1)^{-52}}{52}\right]_{0}^{1}+\left[-\frac{(x-1)^{-53}}{53}\right]_{0}^{1} \end{aligned}$ $\begin{aligned} &=\left[\frac{(x-1)^{-52}}{52}\right]_{0}^{1}+\left[\frac{(x-1)^{-53}}{53}\right]_{0}^{1} \\\\ &=\frac{(-1)^{52}}{52}+\frac{(-1)^{53}}{53} \end{aligned}$ $\begin{aligned} &=\frac{1}{52}-\frac{1}{53}=\frac{1}{52 \times 53} \\\\ &=\frac{1}{2756} \end{aligned}$
Answer: 4 Hint: To solve this we will split $1-x^{2}$ in differential form. Given: $\int_{-2}^{2}\left|1-x^{2}\right| d x$ Solution: $\begin{aligned} &\int_{-2}^{2}\left|1-x^{2}\right| d x \\\\ &1-x^{2}=0 \\\\ &x^{2}=1 \\\\ &x=\pm 1 \end{aligned}$ $\begin{aligned} &=\int_{-2}^{-1}\left(1-x^{2}\right) d x+\int_{-1}^{1}\left(1-x^{2}\right) d x+\int_{1}^{2}\left(1-x^{2}\right) d x \\\\ &=\left[\frac{x^{3}}{3}-x\right]_{-2}^{-1}+\left[x-\frac{x^{3}}{3}\right]_{-1}^{1}+\left[\frac{x^{3}}{3}-x\right]_{1}^{2} \end{aligned}$ $\begin{aligned} &=\left[-\frac{1}{3}+1-\left(-\frac{8}{3}\right)+2\right]+\left[1-\frac{1}{3}-(-1)+\frac{1}{3}\right]+\left[\frac{8}{3}-2-\left(\frac{1}{3}-1\right)\right] \\\\ &=\frac{2}{3}-\left(-\frac{2}{3}\right)+\left[\frac{2}{3}-\left(-\frac{2}{3}\right)\right]+\left[\frac{2}{3}+\frac{2}{3}\right] \end{aligned}$ $\begin{aligned} &=\frac{4}{3}+\frac{4}{3}+\frac{4}{3}+\frac{12}{3} \\\\ &=4 \end{aligned}$
Answer: $\frac{\pi}{4}$ Hint: To solve this equation we should simplify cot x. Given: $\int_{0}^{\frac{\pi}{2}} \frac{1}{1+\cot x} d x$ Solution: Let $\int_{0}^{\frac{\pi}{2}} \frac{1}{1+\cot x} d x$ $I=\int_{0}^{\frac{\pi}{2}} \frac{1}{1+\frac{\cos x}{\sin x}} d x, \quad\left[\therefore \cot x=\frac{\cos x}{\sin x}\right]$ $=\int_{0}^{\frac{\pi}{2}} \frac{\sin x}{\cos x+\sin x} d x \ldots(i), \quad\left[\therefore \int_{0}^{a} f(x) d x=\int_{0}^{a} f(a-x) d x\right]$ $=\int_{0}^{\frac{\pi}{2}} \frac{\sin \left(\frac{\pi}{2}-x\right)}{\cos \left(\frac{\pi}{2}-x\right)+\sin \left(\frac{\pi}{2}-x\right)} d x$ $=\int_{0}^{\frac{\pi}{2}} \frac{\cos x}{\cos x+\sin x} d x \ldots(i i)$ Adding (i) and (ii) $\begin{aligned} &2 I=\int_{0}^{\frac{\pi}{2}} \frac{\cos x+\sin x}{\cos x+\sin x} d x \\\\ &2 I=\int_{0}^{\frac{\pi}{2}} 1 d x \end{aligned}$ $\begin{aligned} &I=\frac{1}{2}[x]_{0}^{\frac{\pi}{2}} \\\\ &I=\frac{1}{2}\left[\frac{\pi}{2}-0\right] \\\\ &=\frac{\pi}{4} \end{aligned}$
Answer: $\frac{\pi }{4}$ Hint: To solve this equation we use $\int_{b}^{a} f(x) d x$ formula. Given: $\int_{0}^{\frac{\pi}{2}} \frac{\sin x}{\sin x+\cos x} d x$ Solution: Let $\begin{aligned} &I=\int_{0}^{\frac{\pi}{2}} \frac{\sin x}{\sin x+\cos x} d x \ldots(i) \\\\ &\int_{0}^{\frac{\pi}{2}} f(x) d x=\int_{0}^{\frac{\pi}{2}} f\left(\frac{\pi}{2}-x\right) d x \end{aligned}$ $\begin{aligned} &=\int_{0}^{\frac{\pi}{2}} \frac{\sin \left(\frac{\pi}{2}-x\right)}{\sin \left(\frac{\pi}{2}-x\right)+\cos \left(\frac{\pi}{2}-x\right)} d x \\\\ &=\int_{0}^{\frac{\pi}{2}} \frac{\cos x}{\cos x+\sin x} d x \ldots(i i) \end{aligned}$ Adding (i) and (ii) $\begin{aligned} &2 I=\int_{0}^{\frac{\pi}{2}} \frac{\sin x}{\sin x+\cos x} d x+\int_{0}^{\frac{\pi}{2}} \frac{\cos x}{\cos x+\sin x} d x \\\\ &=\int_{0}^{\frac{\pi}{2}} \frac{1}{\sin x+\cos x}[\cos x+\sin x] d x \end{aligned}$ $\begin{aligned} &2 I=\int_{0}^{\frac{\pi}{2}} 1 d x \\\\ &2 I=[x]_{0}^{\frac{\pi}{2}} \end{aligned}$ $\begin{aligned} &2 I=\left[\frac{\pi}{2}-0\right] \\\\ &=\frac{\pi}{2} \times \frac{1}{2} \\\\ &I=\frac{\pi}{4} \end{aligned}$
Answer: $\frac{\pi }{2}$ Hint: To solve this equation we use $\int_{a}^{b} \frac{d}{d x} f(x) d x$ formula. Given: $\int_{0}^{1} \frac{d}{d x}\left\{\sin ^{-1}\left(\frac{2 x}{1+x^{2}}\right)\right\} d x$ Solution: Let $\begin{aligned} I &=\int_{0}^{1} \frac{d}{d x}\left\{\sin ^{-1}\left(\frac{2 x}{1+x^{2}}\right)\right\} d x \\\\ &=\int_{0}^{1} \frac{d}{d x}\left(2 \tan ^{-1} x\right) d x \end{aligned}$ $\begin{aligned} &=2 \int_{0}^{1} \frac{d}{d x}\left(\tan ^{-1} x\right) d x \\\\ &=2 \int_{0}^{1} \frac{1}{1+x^{2}} d x \end{aligned}$ $\begin{aligned} &=2\left[\tan ^{-1} x\right]_{0}^{1} \\\\ &=2\left[\tan ^{-1} 1-\tan ^{-1} 0\right] \\\\ &=2\left[\frac{\pi}{4}\right]-0 \\\\ &=\frac{\pi}{2} \end{aligned}$
Answer: 1 Hint: To solve this equation we suppose sin x as cos x. Given: $\int_{0}^{\frac{\pi}{2}} x \sin x \; d x$ Solution: Let $I=\int_{0}^{\frac{\pi}{2}} x \sin x \; d x$ $\begin{aligned} &=\left[x \int \sin x \; d x+\int \cos x \; d x\right]_{0}^{\pi / 2} \\\\ &=[-x \cos x+\sin x]_{0}^{\pi / 2} \end{aligned}$ $\begin{aligned} &=-\frac{\pi}{2} \cos \frac{\pi}{2}+\sin \frac{\pi}{2}-0 \\\\ &=-\frac{\pi}{2} \cos \frac{\pi}{2}+1 \\\\ &=0+1=1 \end{aligned}$
Answer: 0 Hint: To solve this equation we use $\int_{a}^{b} f(x) d x$ formula. Given: $\int_{0}^{\frac{\pi}{2}} \sin 2 x \log \tan x \; d x$ Solution: Let $\begin{aligned} &I=\int_{0}^{\frac{\pi}{2}} \sin 2 x \log \tan x \; d x \ldots(i) \\\\ &\int_{a}^{b} f(x) d x=\int_{a}^{b} f(a+b-x) d x \end{aligned}$ $\begin{aligned} &I=\int_{0}^{\frac{\pi}{2}} \sin 2\left(\frac{\pi}{2}-x\right) \cdot \log \left[\tan \left(\frac{\pi}{2}-x\right)\right] d x \\\\ &=\int_{0}^{\frac{\pi}{2}} \sin (\pi-2 x) \cdot \log \cot x \; d x \end{aligned}$ $=\int_{0}^{\frac{\pi}{2}} \sin 2 x \cdot \log \cot x\; d x \ldots(i i)$ Adding (i) and (ii) $2 I=\int_{0}^{\frac{\pi}{2}} \sin 2 x \cdot \log \tan x+\sin 2 x \cdot \log \cot x \; d x$ $\begin{aligned} &2 I=\int_{0}^{\frac{\pi}{2}} \sin 2 x(\log \tan x+\log \cot x) d x \\\\ &2 I=\int_{0}^{\frac{\pi}{2}} \sin 2 x(\log \tan x \cdot \cot x) d x \end{aligned}$ $\begin{aligned} &\log a \cdot b=\log a+\log b \\\\ &2 I=\int_{0}^{\frac{\pi}{2}} \sin 2 x\left(\log \tan x \cdot \frac{1}{\tan x}\right) d x \end{aligned}$ $\begin{aligned} &2 I=\int_{0}^{\frac{\pi}{2}} \sin 2 x(\log 1) d x \\\\ &2 I=0 \\\\ &I=0 \end{aligned}$
Answer: $\int_{a}^{2 a} f(x) d x=\int_{0}^{a} f(x) d x+\int_{0}^{2 a}f(2 a-x) d x$ Hint: Given: $\int_{a}^{2 a} f(x) d x$ Solution: $\int_{a}^{2 a} f(x) d x$ $\begin{aligned} &f(2 a-x)=f(x) \\\\ &\int_{0}^{a} 2 f(x) d x \end{aligned}$ $\begin{aligned} &=2 \int_{0}^{a} f(x) d x \\\\ &\int_{a}^{2 a} f(x) d x=\int_{0}^{a} f(x) d x+\int_{0}^{2 a}f(2 a-x) d x \end{aligned}$
Answer: $I=\frac{a+b}{2} \int_{a}^{b} f(x) d x$ Hint: To solve this we will split (a+b-x) Given: $\int(a+b-x)=f(x)$ Solution: $\int(a+b-x)=f(x)$ Let $\begin{aligned} &I=\int_{a}^{b} x \cdot f(x) d x \ldots(i) \\\\ &\int_{a}^{b} f(x) d x=\int_{a}^{b}(a+b-x) d x \end{aligned}$ $\begin{aligned} &I=\int_{a}^{b}(a+b-x) \cdot f(a+b-x) d x \\\\ &I=\int_{a}^{b}(a+b-x) \cdot f(x) d x \end{aligned}$ $I=\int_{a}^{b}(a+b) \cdot f(x) d x-\int_{a}^{b} x f(x) d x \ldots(i i)$ Adding equation (i) and (ii) $I+I=\int_{a}^{b} x f(x) d x+\int_{a}^{b}(a+b) \cdot f(x) d x-\int_{a}^{b} x f(x) d x$ $\begin{aligned} &2 I=\int_{a}^{b}(a+b) f(x) d x \\\\ &I=\frac{1}{2} \int_{a}^{b}(a+b) f(x) d x \\\\ &I=\frac{a+b}{2} \int_{a}^{b}(a+b) f(x) d x \end{aligned}$
Answer: 0 Hint: Given: $\int_{0}^{1} \tan ^{-1}\left(\frac{2 x-1}{1+x-x^{2}}\right) d x$ Explanation: $\begin{aligned} I &=\int_{0}^{1} \tan ^{-1}\left(\frac{2 x-1}{1-x-x^{2}}\right) d x \\\\ &=\int_{0}^{1} \tan ^{-1}\left[\frac{x-(1-x)}{1+x(1-x)}\right] d x \end{aligned}$ $=\int_{0}^{1} \tan ^{-1} x-\tan ^{-1}(1-x) d x$ .........Eq(i) Using properties, $\begin{aligned} &\int_{0}^{a} f(x) d x=\int_{0}^{a} f(a-x) d x \\\\ &I=\int_{0}^{1} \tan ^{-1}(1-x)-\tan ^{-1}(1-(1-x)) d x \end{aligned}$ $=\int_{0}^{1} \tan ^{-1}(1-x)-\tan ^{-1} x \; d x$ ..........Eq(ii) Adding Eq(i) and Eq(ii) $\begin{aligned} &2 I=0 \\\\ &I=0 \end{aligned}$
Answer: $I=0$ Hint: To solve this equation we use $\int_{0}^{a} f(x) d x$ formula. Given: $\int_{0}^{\frac{\pi}{2}} \log \left[\frac{4+3 \sin x}{4+3 \cos x}\right] d x$ Solution: Let $\begin{aligned} &I=\int_{0}^{\frac{\pi}{2}} \log \left[\frac{4+3 \sin x}{4+3 \cos x}\right] d x \ldots(i) \\\\ &\int_{0}^{a} f(x) d x=\int_{0}^{a}(a-x) d x \end{aligned}$ $\begin{aligned} &I=\int_{0}^{\frac{\pi}{2}} \log \left[\frac{4+3 \sin \left(\frac{\pi}{2}-x\right)}{4+3 \cos \left(\frac{\pi}{2}-x\right)}\right] d x \\\\ &I=\int_{0}^{\frac{\pi}{2}} \log \left[\frac{4+3 \cos x}{4+3 \sin x}\right] d x \ldots(i i) \end{aligned}$ Adding (i) and (ii) $\begin{aligned} &2 I=\int_{0}^{\frac{\pi}{2}}\left(\log \left[\frac{4+3 \cos x}{4+3 \sin x}\right]+\log \left[\frac{4+3 \sin x}{4+3 \cos x}\right]\right) d x \\\\ &2 I=\int_{0}^{\frac{\pi}{2}}\left(\log \left[\frac{4+3 \cos x}{4+3 \sin x}\right] \cdot \log \left[\frac{4+3 \sin x}{4+3 \cos x}\right]\right) d x \end{aligned}$ $\begin{aligned} &2 I=\int_{0}^{\frac{\pi}{2}} 1 d x \\\\ &2 I=0 \\\\ &I=0 \end{aligned}$
Answer: $\pi$ Hint: We use $\int_{-a}^{a} f(x) d x=0$ function. Given: $\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}\left(x^{3}+x \cos x+\tan ^{5} x+1\right) d x$ Explanation: $\begin{aligned} &\int_{-a}^{a} f(x) d x=0\\\\ &f(x) \text { odd function }\\\\ &f(-x)=-f(x)\\\\ &(-x)^{3}=-x^{3} \ldots(i) \end{aligned}$ $\begin{aligned} &x \cos x \\\\ &(-x) \cos (-x)=-x \cos x \ldots(i i) \\\\ &\tan ^{5} x \\\\ &\tan ^{5}(-x)=-\tan ^{5} x \ldots(i i i) \end{aligned}$ $\begin{aligned} &=\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} x^{3} d x+\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} x \cos x d x+\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} \tan ^{5} x d x+\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} 1 d x \\\\ &=\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} 1 d x \end{aligned}$ $\begin{aligned} &=[x]_{-\frac{\pi}{2}}^{\frac{\pi}{2}} \\\\ &=\frac{\pi}{2}-\left(-\frac{\pi}{2}\right) \\\\ &=\frac{2 \pi}{2} \\\\ &=\pi \end{aligned}$
Answer: $\int_{a}^{b} f(x+c) d x$ Hint: To solve this $\int_{a}^{b} f(x) d x$ formula is used. Given: $\int_{a+c}^{b+c} f(x) d x$ Explanation: $\int_{a+c}^{b+c} f(x) d x$ $\begin{aligned} &=f[x]_{a+c}^{b+c} \\ \\ &=f(b+c)-f(a+c) \end{aligned}$ Now, solving option (b), $\begin{aligned} &\int_{a}^{b} f(x+c) d x \\\\ &=[f(x+c)]_{a}^{b} \\\\ &=f(b+c)-f(a+c) \end{aligned}$ Hence, option (b) is correct.
Answer: $\frac{a}{2} \int_{0}^{a} f(x) d x$ Hint: To solve this equation we use $\int_{0}^{a} f(x) d x$ formula. Given: $f(x)=f(a-x), \quad g(x)+g(a-x)=a$ Explanation: $\begin{aligned} &I=\int_{0}^{a} g(x) f(x) d x \ldots(i) \\\\ &\text { Put } x=(a-x) \\\\ &=\int_{0}^{a} g(a-x) f(a-x) d x \ldots(i i) \end{aligned}$ $\begin{aligned} &=\int_{0}^{a} f(x)(a-g(x)) d x \\\\ &I=a \int_{0}^{a} f(x) d x-\int_{0}^{a} f(x) \cdot g(x) d x \end{aligned}$ $\begin{gathered} I=a \int_{0}^{a} f(x) d x-I \\\\ 2 I=a \int_{0}^{a} f(x) d x \\\\ I=\frac{a}{2} \int_{0}^{a} f(x) d x \end{gathered}$
Answer: 1 Hint: To solve this question we have to use substitution method. Given: $\int_{0}^{1} \tan \left(\sin ^{-1} x\right) d x$ Explanation: $\begin{aligned} &\sin ^{-1} x=t \\\\ &x=\sin t \\\\ &d x=\cos t d t \\\\ &\text { When } x=0, \sin ^{-1} 0=0 \\\\ &\text { When } x=1, \sin ^{-1} 1=\frac{\pi}{2} \end{aligned}$ $\begin{aligned} &I=\int_{0}^{\frac{\pi}{2}} \tan t \cdot \cos t \; d t \\\\ &\frac{\sin t}{\cos t}=\tan t \\\\ &\sin t=\cos t \cdot \cos t \end{aligned}$ $\begin{aligned} &=\int_{0}^{\frac{\pi}{2}} \sin t d t \\\\ &I=[-\cos t]_{0}^{\frac{\pi}{2}} \\\\ &I=0-(-1) \\\\ &=1 \end{aligned}$
The RD Sharma class 12 solution of Definite integrals exercise MCQ covers the chapter 'Definite Integrals.' There are about 46 MCQs in this exercise which gives a brief insight of the chapter. The RD Sharma class 12th exercise MCQ covers all the essential concepts like,
Limit sum of definite integrals
Fundamentals of a theorem in definite integral
Basic properties
Evaluation method of integrals
The beneficial factors of using the RD Sharma class 12 solution chapter 19 exercise MCQ are :-
RD Sharma class 12th exercise MCQ is available for download on the careers360 website, you can visit the site for free PDFs and study materials.
Any student who has previously used the RD Sharma class 12 chapter 19 exercise MCQ solution for practicing will always raise the study material of RD Sharma as it has always helped them to score better and to understand maths easily.
The RD Sharma class 12th exercise MCQ contains questions that are prepared by maths experts with some helpful tips to solve the questions easily.
Any student can refer to the RD Sharma class 12th exercise MCQ solution for solving questions that they find trouble in as the solution provides solved question examples for the betterment of the students.
Every student should make use of the RD Sharma class 12th exercise MCQ to stay ahead of the class as most of the Teacher's take reference of the solution to provide lectures and prepare question papers.
JEE Main Highest Scoring Chapters & Topics
Focus on high-weightage topics with this eBook and prepare smarter. Gain accuracy, speed, and a better chance at scoring higher.