If $y = x \sin x$, then $y_2 = \dfrac{d^2y}{dx^2}$ equals:
A$-x\sin x$
B$x\cos x$
C$2\cos x - x \sin x$
D$\cos x + \sin x$
Answer & Solution
Correct answer: C. $2\cos x - x \sin x$
$y' = \sin x + x\cos x$. $y'' = \cos x + \cos x + x(-\sin x) = 2\cos x - x\sin x$.
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