If $y = \sin x$, then $y_n = \dfrac{d^n y}{dx^n}$ at $x = 0$ for $n = 4$ equals:
A$-1$
B$0$
C$1$
D$\sin(0) = 0$
Answer & Solution
Correct answer: B. $0$
$d/dx(\sin x)$ cycles every 4: $\sin, \cos, -\sin, -\cos, \sin, \dots$. So $y^{(4)} = \sin x$. At $x=0$: $\sin 0 = 0$.
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