# Math Help - differentiation

1. ## differentiation

The first part of the question is differentiate x(x-4)(x+4) which I can do:
Dy/dx = 3x²-16
But the next part is differentiate 1/x² with respect to x
Which I do not understand

Thanks

2. Differentiate y with respect to x means $\frac {dy}{dx}$.

So differentiate $\frac {1}{x^2}$ with respect to x means

$\frac {d \frac {1}{x^2}}{dx}$

$\frac{{dx}^{-2}}{{dx}}$

$-2 x^{-3}$

$-\frac {2}{x^{3}}$