Question

Find the second order derivatives of $x^{20}$

Answer 1

Let $y=x^{20}$
$\Rightarrow \frac{dy}{dx}=\frac{d}{dx}\left(x^{20}\right)=20x^{19}$
$\therefore \frac{d^{2}y}{d{x}^2}=\frac{d}{dx}\left(20x^{19}\right)=20\frac{d}{dx}\left(x^{19}\right)=20.19x^{18}=380x^{18}$