Question

Find the derivative of $2x^4+x$.

• A. $x^3+1$
• B. $8x^3+1$
• C. $x^3-1$
• D. None of these

Answer 1

Answer: (B)

Let $y=2x^4+x\dots \left(i\right)$
Differentiating $\left(i\right)$ both sides with respect to $x$, we get
$\frac{dy}{dx}=\frac{d}{dx}\left(2x^4\right)+\frac{d}{dx}\left(x\right)$
$=2\times 4x^3+1=8x^3+1$