# Math Help - prove f(x) is constant

1. ## prove f(x) is constant

Can someone explain to me where the (-1/x^2) comes from in step 2 and why?
It is in the attached image.
Thanks for any input.

2. Originally Posted by jlmills5
Can someone explain to me where the (-1/x^2) comes from in step 2 and why? It is in the attached image.
Using the chain rule the factor $\frac {-1}{x^2}$ is the derivative of $\frac {1}{x}$.

3. of course. thank you.