Question

If $y=2\sin x-3x^4+8$, then $\frac{dy}{dx}$ is

• A. $2\sin x-12x^3$
• B. $2\cos x-12x^3$
• C. $2\cos x+12x^3$
• D. $2\sin x+12x^3$

Answer 1

The correct option is B $2\cos x-12x^3$

If $y=2\sin x-3x^4+8$
$\Rightarrow \frac{dy}{dx}=2\cos x-3\left(4x^{(4-1)}\right)+0$
$\Rightarrow \frac{dy}{dx}=2\cos x-12x^3$
Therefore, the correct answer is $B$.