Integral Calculus Question 447

Question: $ \int_{{}}^{{}}{x\cos x^{2}\ dx} $ is equal to

[MP PET 1999; Pb. CET 2000]

Options:

A) $ -\frac{1}{2}{{\sin }^{2}}x+c $

B) $ \frac{1}{2}{{\sin }^{2}}x+c $

C) $ -\frac{1}{2}\sin x^{2}+c $

D) $ \frac{1}{2}\sin x^{2}+c $

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Answer:

Correct Answer: D

Solution:

Put $ x^{2}=t\Rightarrow dt=2x,dx $ \ Given integral $ =\frac{1}{2}\int_{{}}^{{}}{\cos t,dt}=\frac{1}{2}\sin t=\frac{1}{2}\sin x^{2}+c $ .