Differentiation Class 12 Maths 2 Exercise 1.5 Solutions Maharashtra Board

Balbharti 12th Maharashtra State Board Maths Solutions Book Pdf Chapter 1 Differentiation Ex 1.5 Questions and Answers.

12th Maths Part 2 Differentiation Exercise 1.5 Questions And Answers Maharashtra Board

Question 1.
Find the second order derivatives of the following:
(i) 2x 5 – 4x 3 – \(\frac{2}{x^{2}}\) – 9
Solution:
Let y = 2x 5 – 4x 3 – \(\frac{2}{x^{2}}\) – 9
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-i
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-i.1

(ii) e 2x . tan x
Solution:
Let y = e 2x . tan x
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-ii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-ii.1

Maharashtra-Board-Solutions

(iii) e 4x . cos 5x
Solution:
Let y = e 4x . cos 5x
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-iii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-iii.1

(iv) x 3 . log x
Solution:
Let y = x 3 . log x
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-iv

(v) log(log x)
Solution:
Let y = log(log x)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-v
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-v.1

(vi) x x
Solution:
y = x x
log y = log x x = x log x
Differentiating both sides w.r.t. x, we get
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q1-vi

Question 2.
Find \(\frac{d^{2} y}{d x^{2}}\) of the following:
(i) x = a(θ – sin θ), y = a (1 – cos θ)
Solution:
x = a(θ – sin θ), y = a (1 – cos θ)
Differentiating x and y w.r.t. θ, we get
\(\frac{d x}{d \theta}=a \frac{d}{d \theta}(\theta-\sin \theta)\) = a(1 – cos θ) …….(1)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q2-i

(ii) x = 2at 2 , y = 4at
Solution:
x = 2at 2 , y = 4at
Differentiating x and y w.r.t. t, we get
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q2-ii

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(iii) x = sin θ, y = sin 3 θ at θ = \(\frac{\pi}{2}\)
Solution:
x = sin θ, y = sin 3 θ
Differentiating x and y w.r.t. θ, we get,
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q2-iii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q2-iii.1

(iv) x = a cos θ, y = b sin θ at θ = \(\frac{\pi}{4}\)
Solution:
x = a cos θ, y = b sin θ
Differentiating x and y w.r.t. θ, we get
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q2-iv
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q2-iv.1
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q2-iv.2

Question 3.
(i) If x = at 2 and y = 2at, then show that \(x y \frac{d^{2} y}{d x^{2}}+a=0\)
Solution:
x = at 2 , y = 2at ………(1)
Differentiating x and y w.r.t. t, we get
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-i
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-i.1

(ii) If y = \(e^{m \tan ^{-1} x}\), show that \(\left(1+x^{2}\right) \frac{d^{2} y}{d x^{2}}+(2 x-m) \frac{d y}{d x}=0\)
Solution:
y = \(e^{m \tan ^{-1} x}\) ……..(1)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-ii

(iii) If x = cos t, y = e mt , show that \(\left(1-x^{2}\right) \frac{d^{2} y}{d x^{2}}-x \frac{d y}{d x}-m^{2} y=0\)
Solution:
x = cos t, y = e mt
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-iii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-iii.1

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(iv) If y = x + tan x, show that \(\cos ^{2} x \cdot \frac{d^{2} y}{d x^{2}}-2 y+2 x=0\)
Solution:
y = x + tan x
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-iv

(v) If y = e ax . sin (bx), show that y 2 – 2ay 1 + (a 2 + b 2 )y = 0.
Solution:
y = e ax . sin (bx) ………(1)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-v
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-v.1

(vi) If \(\sec ^{-1}\left(\frac{7 x^{3}-5 y^{3}}{7 x^{3}+5 y^{3}}\right)=m\), show that \(\frac{d^{2} y}{d x^{2}}=0\)
Solution:
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-vi
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-vi.1
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-vi.2

(vii) If 2y = \(\sqrt{x+1}+\sqrt{x-1}\), show that 4(x 2 – 1)y 2 + 4xy 1 – y = 0.
Solution:
2y = \(\sqrt{x+1}+\sqrt{x-1}\) …… (1)
Differentiating both sides w.r.t. x, we get
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-vii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-vii.1

(viii) If y = \(\log \left(x+\sqrt{x^{2}+a^{2}}\right)^{m}\), show that \(\left(x^{2}+a^{2}\right) \frac{d^{2} y}{d x^{2}}+x \frac{d y}{d x}=0\)
Solution:
y = \(\log \left(x+\sqrt{x^{2}+a^{2}}\right)^{m}\) = \(m \log \left(x+\sqrt{x^{2}+a^{2}}\right)\)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-viii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-viii.1

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(ix) If y = sin(m cos -1 x), then show that \(\left(1-x^{2}\right) \frac{d^{2} y}{d x^{2}}-x \frac{d y}{d x}+m^{2} y=0\)
Solution:
y = sin(m cos -1 x)
sin -1 y = m cos -1 x
Differentiating both sides w.r.t. x, we get
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-ix

(x) If y = log(log 2x), show that xy 2 + y 1 (1 + xy 1 ) = 0.
Solution:
y = log(log 2x)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-x
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-x.1
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-x.2

(xi) If x 2 + 6xy + y 2 = 10, show that \(\frac{d^{2} y}{d x^{2}}=\frac{80}{(3 x+y)^{3}}\)
Solution:
x 2 + 6xy + y 2 = 10 …… (1)
Differentiating both sides w.r.t. x, we get
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-xi
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-xi.1
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-xi.2

(xii) If x = a sin t – b cos t, y = a cos t + b sin t, Show that \(\frac{d^{2} y}{d x^{2}}=-\frac{x^{2}+y^{2}}{y^{3}}\)
Solution:
x = a sin t – b cos t, y = a cos t + b sin t
Differentiating x and y w.r.t. t, we get
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-xii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q3-xii.1

Maharashtra-Board-Solutions

Question 4.
Find the nth derivative of the following:
(i) (ax + b) m
Solution:
Let y = (ax + b) m
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-i
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-i.1
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-i.2

(ii) \(\frac{1}{x}\)
Solution:
Let y = \(\frac{1}{x}\)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-ii

(iii) e ax+b
Solution:
Let y = e ax+b
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-iii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-iii.1

(iv) a px+q
Solution:
Let y = a px+q
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-iv

Maharashtra-Board-Solutions

(v) log(ax + b)
Solution:
Let y = log(ax + b)
Then \(\frac{d y}{d x}=\frac{d}{d x}[\log (a x+b)]\)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-v

(vi) cos x
Solution:
Let y = cos x
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-vi

(vii) sin(ax + b)
Solution:
Let y = sin(ax + b)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-vii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-vii.1

(viii) cos(3 – 2x)
Solution:
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-viii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-viii.1

(ix) log(2x + 3)
Solution:
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-ix
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-ix.1

(x) \(\frac{1}{3 x-5}\)
Solution:
Let y = \(\frac{1}{3 x-5}\)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-x
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-x.1

Maharashtra-Board-Solutions

(xi) y = e ax . cos (bx + c)
Solution:
y = e ax . cos (bx + c)
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-xi
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-xi.1
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-xi.2
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-xi.3
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-xi.4

(xii) y = e 8x . cos (6x + 7)
Solution:
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-xii
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-xii.1
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-xii.2
Maharashtra-Board-12th-Maths-Solutions-Chapter-1-Differentiation-Ex-1.5-Q4-xii.3