NCERT Solutions
Class 11 - Mathematics - Chapter 12: LIMITS AND DERIVATIVES
Miscellaneous Exercise on Chapter 12

Question. 1

Find the derivative of the following functions from first principle:

(i) \(-x\)

(ii) \((-x)^{-1}\)

(iii) \(\sin (x+1)\)

(iv) \(\cos \left(x-\tfrac{\pi}{8}\right)\)

Answer:

(i) \(-1\)

(ii) \(\dfrac{1}{x^{2}}\)

(iii) \(\cos (x+1)\)

(iv) \(-\sin \left(x-\tfrac{\pi}{8}\right)\)

Question. 2

Find the derivative of \(x+a\).

Answer:

1

Question. 3

Find the derivative of \((px+q)\left(\dfrac{r}{x}+s\right)\), where \(p,q,r,s\) are fixed non-zero constants.

Answer:

\(-\dfrac{qr}{x^{2}}+ps\)

Question. 4

Find the derivative of \((ax+b)(cx+d)^{2}\).

Answer:

\(2c(ax+b)(cx+d)+a(cx+d)^{2}\)

Question. 5

Find the derivative of \(\dfrac{ax+b}{cx+d}\).

Answer:

\(\dfrac{ad-bc}{(cx+d)^{2}}\)

Question. 6

Find the derivative of \(\dfrac{1+\tfrac{1}{x}}{1-\tfrac{1}{x}}\).

Answer:

\(-\dfrac{2}{(x-1)^{2}},\ x\neq 0,1\)

Question. 7

Find the derivative of \(\dfrac{1}{ax^{2}+bx+c}\).

Answer:

\(-\dfrac{2ax+b}{(ax^{2}+bx+c)^{2}}\)

Question. 8

Find the derivative of \(\dfrac{ax+b}{px^{2}+qx+r}\).

Answer:

\(-\dfrac{apx^{2}+2bpx+ar-bq}{(px^{2}+qx+r)^{2}}\)

Question. 9

Find the derivative of \(\dfrac{px^{2}+qx+r}{ax+b}\).

Answer:

\(\dfrac{apx^{2}+2bpx+bq-ar}{(ax+b)^{2}}\)

Question. 10

Find the derivative of \(\dfrac{a}{x^{4}}-\dfrac{b}{x^{2}}+\cos x\).

Answer:

\(-\dfrac{4a}{x^{5}}+\dfrac{2b}{x^{3}}-\sin x\)

Question. 11

Find the derivative of \(4\sqrt{x}-2\).

Answer:

\(\dfrac{2}{\sqrt{x}}\)

Question. 12

Find the derivative of \((ax+b)^{n}\).

Answer:

\(na(ax+b)^{n-1}\)

Question. 13

Find the derivative of \((ax+b)^{n}(cx+d)^{m}\).

Answer:

\((ax+b)^{n-1}(cx+d)^{m-1}\big[mc(ax+b)+na(cx+d)\big]\)

Question. 14

Find the derivative of \(\sin(x+a)\).

Answer:

\(\cos(x+a)\)

Question. 15

Find the derivative of \(\csc x\cot x\).

Answer:

\(-\csc^{3}x-\csc x\cot^{2}x\)

Question. 16

Find the derivative of \(\dfrac{\cos x}{1+\sin x}\).

Answer:

\(-\dfrac{1}{1+\sin x}\)

Question. 17

Find the derivative of \(\dfrac{\sin x+\cos x}{\sin x-\cos x}\).

Answer:

\(-\dfrac{2}{(\sin x-\cos x)^{2}}\)

Question. 18

Find the derivative of \(\dfrac{\sec x-1}{\sec x+1}\).

Answer:

\(\dfrac{2\sec x\tan x}{(\sec x+1)^{2}}\)

Question. 19

Find the derivative of \(\sin^{n}x\).

Answer:

\(n\sin^{n-1}x\cos x\)

Question. 20

Find the derivative of \(\dfrac{a+b\sin x}{c+d\cos x}\).

Answer:

\(\dfrac{bc\cos x+ad\sin x+bd}{(c+d\cos x)^{2}}\)

Question. 21

Find the derivative of \(\dfrac{\sin(x+a)}{\cos x}\).

Answer:

\(\dfrac{\cos a}{\cos^{2}x}\)

Question. 22

Find the derivative of \(x^{4}(5\sin x-3\cos x)\).

Answer:

\(x^{3}\big(5x\cos x+3x\sin x+20\sin x-12\cos x\big)\)

Question. 23

Find the derivative of \((x^{2}+1)\cos x\).

Answer:

\(-x^{2}\sin x-\sin x+2x\cos x\)

Question. 24

Find the derivative of \((ax^{2}+\sin x)(p+q\cos x)\).

Answer:

\(-q\sin x(ax^{2}+\sin x)+(p+q\cos x)(2ax+\cos x)\)

Question. 25

Find the derivative of \((x+\cos x)(x-\tan x)\).

Answer:

\(-\tan^{2}x(x+\cos x)+(x-\tan x)(1-\sin x)\)

Question. 26

Find the derivative of \(\dfrac{4x+5\sin x}{3x+7\cos x}\).

Answer:

\(\dfrac{35+15x\cos x+28\cos x+28x\sin x-15\sin x}{(3x+7\cos x)^{2}}\)

Question. 27

Find the derivative of \(\dfrac{x^{2}\cos\left(\tfrac{\pi}{4}\right)}{\sin x}\).

Answer:

\(\dfrac{x\cos\left(\tfrac{\pi}{4}\right)(2\sin x-x\cos x)}{\sin^{2}x}\)

Question. 28

Find the derivative of \(\dfrac{x}{1+\tan x}\).

Answer:

\(\dfrac{1+\tan x-x\sec^{2}x}{(1+\tan x)^{2}}\)

Question. 29

Find the derivative of \((x+\sec x)(x-\tan x)\).

Answer:

\((x+\sec x)(1-\sec^{2}x)+(x-\tan x)(1+\sec x\tan x)\)

Question. 30

Find the derivative of \(\dfrac{x}{\sin^{n}x}\).

Answer:

\(\dfrac{\sin x-nx\cos x}{\sin^{n+1}x}\)

NCERT Solutions Class 11 – Mathematics – Chapter 12: LIMITS AND DERIVATIVES – Miscellaneous Exercise on Chapter 12 | Detailed Answers