1. ## derivatives

For positive constants A and B, the force between two atoms in a molecule is given by the following equation, where r > 0 is the distance between the atoms.

Find f '(r).

Find the critical point for f(r).

2. Originally Posted by mer1988
For positive constants A and B, the force between two atoms in a molecule is given by the following equation, where r > 0 is the distance between the atoms.

Find f '(r).

Find the critical point for f(r).
rewrite as $f(r) = -Ar^{-2} + Br^{-3}$

now use the power rule to find $f'(r)$

to find the critical points, set $f'(r) = 0$ and solve for $r$