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KC Sinha Mathematics Solution Class 12 Chapter 11 अवकलन (Differentiation) Exercise 11.5 (Q16-Q18)

Exercise 11.5










Question 16

\frac{x}{\sin x} का sinx के सापेक्ष अवकलन गुणांक निकाले ।
[Find the derivative of \frac{x}{\sin x} w.r.t sin x]
Sol :
माना u=\frac{x}{\sin x} , v=sinx

Differentiating w.r.t x

\frac{d u}{d x}=\frac{1 \sin x-x \cdot \cos x}{\sin ^{2} x}

\frac{d u}{d x}=\frac{\sin x-x \cos x}{\sin ^{2} x}..(i)

v=sinx

Differentiating w.r.t x

\frac{d v}{d x}=\cos x..(i)

समीकरण (i) मे (ii) से भाग देने पर ,

\frac{\frac{d y}{d x}}{\frac{dv}{dx}}=\frac{\frac{\sin x-x \cos x}{\sin ^{2} x}}{\cos x}

\frac{du}{d v}=\frac{\sin x-x \cos x}{\sin ^{2} x \cos x}


Question 17

\sqrt{\sin \left(1+x^{2}\right)^{2}} का 1+x2 के सापेक्ष अवकलन गुणांक ज्ञात करे ।
[Find the d.c. of $\sqrt{\sin \left(1+x^{2}\right)^{2}} w.r.t 1+x^2$]
Sol :
माना u=\sqrt{\sin \left(1+x^{2}\right)^{2}} ,v=1+x2

Differentiating w.r.t x

\frac{d u}{d x}=\frac{1}{2 \sqrt{\sin \left(1+x^{2}\right)^{2}}} \times \cos \left(1+x^{2}\right)^{2} \times 2\left(1+x^{2}\right) \cdot 2 x

\frac{d u}{d x}=\frac{2 x\left(1+x^{2}\right) \cdot \cos \left(1+x^{2}\right)^{2}}{\sqrt{\sin \left(1+x^{2}\right)^{2}}}..(i)

अब,

v=1+x2

Differentiating w.r.t x

\frac{d v}{d x}=2 x..(ii)

समीकरण (i) मे (ii) से भाग देने पर ,

\frac{\frac{d u}{d v}}{\frac{dv}{dx}}=\frac{\frac{2x\left(1+x^{2}\right) \cos \left(1+x^{2}\right)^{2}}{\sqrt{\sin \left(1+x^{2}\right)^{2}}}}{2x}

\frac{d u}{d v}=\frac{\left(1+t^{2}\right) \cdot \cos \left(1+x^{2}\right)^{2}}{\sqrt{\sin \left(1+x^{2}\right)^{2}}}


Question 18

\tan ^{-1} \frac{2 x}{1-x^{2}} का \cos ^{-1} \frac{1-x^{2}}{1+x^{2}} के सापेक्ष अवकलन गुणांक निकालें जहाँ |x|<1
[Find the d.c. of \tan ^{-1} \frac{2 x}{1-x^{2}} w.r.t \cos ^{-1} \frac{1-x^{2}}{1+x^{2}} where |x|<1]
Sol :
माना u=\tan ^{-1} \frac{2 x}{1-x^{2}} v=\cos ^{-1} \frac{1-x^{2}}{1+x^{2}}

u=2tan-1x,v=2tan-1x

Differentiating w.r.t x

\frac{d u}{d x}=\frac{2}{1+x^{2}}..(i)

\frac{d v}{dx}=\frac{2}{1+t^{2}}..(ii)

समीकरण (i) मे (ii) से भाग देने पर ,

\frac{\frac{d u}{d x}}{\frac{d v}{dx}}=\frac{\frac{2}{1+x^{2}}}{\frac{2}{1+x^{2}}}

\frac{d u}{d v}=1


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