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Question

Question: If \(\varphi(x) = \int_{1/x}^{\sqrt{x}}{\sin(t^{2})dt,}\) then \(\varphi^{'}(1) =\)...

If φ(x)=1/xxsin(t2)dt,\varphi(x) = \int_{1/x}^{\sqrt{x}}{\sin(t^{2})dt,} then φ(1)=\varphi^{'}(1) =

A

sin1\sin 1

B

2sin12\sin 1

C

32sin1\frac{3}{2}\sin 1

D

None of these

Answer

32sin1\frac{3}{2}\sin 1

Explanation

Solution

φ(x)=sinxddxxsin1x2ddx(1x)\varphi'(x) = \sin x\frac{d}{dx}\sqrt{x} - \sin\frac{1}{x^{2}}\frac{d}{dx}\left( \frac{1}{x} \right)

=sinx.12x+1x2sin1x2= \sin x.\frac{1}{2\sqrt{x}} + \frac{1}{x^{2}}\sin\frac{1}{x^{2}}

φ(1)=12sin1+sin1=32sin1\varphi'(1) = \frac{1}{2}\sin 1 + \sin 1 = \frac{3}{2}\sin 1.