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NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability Ex 5.2

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NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability Ex 5.2 are part of NCERT Solutions for Class 12 Maths. Here we have given NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability Ex 5.2.

Board CBSE
Textbook NCERT
Class Class 12
Subject Maths
Chapter Chapter 5
Chapter Name Continuity and Differentiability
Exercise Ex 5.2
Number of Questions Solved 10
Category NCERT Solutions

NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability Exc  5.2

Differentiate the functions with respect to x in Questions 1 to 8.

Question 1.
sin(x² + 5)
Solution:
Let y = sin(x2 + 5),
put x² + 5 = t
y = sint
t = x²+5
\frac { dy }{ dx } =\frac { dy }{ dt } .\frac { dt }{ dx }
\frac { dy }{ dx } =cost.\frac { dt }{ dx } =cos({ x }^{ 2 }+5)\frac { d }{ dx } ({ x }^{ 2 }+5)
= cos (x² + 5) × 2x
= 2x cos (x² + 5)

Question 2.
cos (sin x)
Solution:
let y = cos (sin x)
put sinx = t
∴ y = cost,
t = sinx
∴\frac { dy }{ dx } =-sin\quad t,\frac { dt }{ dx } =cos\quad x
\frac { dy }{ dx } =\frac { dy }{ dt } .\frac { dt }{ dx } =(-sint)\times cosx
Putting the value of t, \frac { dy }{ dx } =-sin(sinx)\times cosx
\frac { dy }{ dx } =-[sin(sinx)]cosx

Question 3.
sin(ax+b)
Solution:
let = sin(ax+b)
put ax+bx = t
∴ y = sint
t = ax+b
\frac { dy }{ dt } =cost,\frac { dt }{ dx } =\frac { d }{ dx } (ax+b)=a
Now\frac { dy }{ dx } =\frac { dy }{ dt } .\frac { dt }{ dx } =cost\times a=acos\quad t
\frac { dy }{ dx } =acos(ax+b)

Question 4.
sec(tan(√x))
Solution:
let y = sec(tan(√x))
by chain rule
\frac { dy }{ dx } =sec(tan\sqrt { x } )tan(tan\sqrt { x } )\frac { d }{ dx } (tan\sqrt { x } )
\frac { dy }{ dx } =sec(tan\sqrt { x } ).tan(tan\sqrt { x } ){ sec }^{ 2 }\sqrt { x } .\frac { 1 }{ 2\sqrt { x } }

Question 5.
\\ \frac { sin(ax+b) }{ cos(cx+d) }
Solution:
y = \\ \frac { sin(ax+b) }{ cos(cx+d) } = \\ \frac { v }{ u }
u = sin(ax+b)
NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability 5
NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability 5.1

Question 6.
cos x³ . sin²(x5) = y(say)
Solution:
Let u = cos x³ and v = sin² x5,
put x³ = t
NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability 6

Question 7.
2\sqrt { cot({ x }^{ 2 }) } =y(say)
Solution:
2\sqrt { cot({ x }^{ 2 }) } =y(say)
NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability 7

Question 8.
cos(√x) = y(say)
Solution:
cos(√x) = y(say)
\frac { dy }{ dx } =\frac { d }{ dx } cos\left( \sqrt { x } \right) =-sin\sqrt { x } .\frac { d\sqrt { x } }{ dx }
=-sin\sqrt { x } .\frac { 1 }{ 2 } { (x) }^{ -\frac { 1 }{ 2 } }=\frac { -sin\sqrt { x } }{ 2\sqrt { x } }
NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability 8

Question 9.
Prove that the function f given by f (x) = |x – 1|,x ∈ R is not differential at x = 1.
Solution:
The given function may be written as
f(x)=\begin{cases} x-1,\quad if\quad x\ge 1 \\ 1-x,\quad if\quad x<1 \end{cases}
R.H.D\quad at\quad x=1\quad =\underset { h\rightarrow 0 }{ lim } \frac { f(1+h)-f(1) }{ h }

Question 10.
Prove that the greatest integer function defined by f (x)=[x], 0 < x < 3 is not differential at x = 1 and x = 2.
Solution:
(i) At x = 1
R.H.D=\underset { h\rightarrow 0 }{ lim } \frac { f(1+h)-f(1) }{ h }
NCERT Solutions for Class 12 Maths Chapter 5 Continuity and Differentiability 10

 

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