## College Algebra 7th Edition

$r=\pm\sqrt{k\frac{q_{1}q_{2}}{F}}$
We solve the equation for $r$: $F=k\displaystyle \frac{q_{1}q_{2}}{r^{2}}$ First we multiply by $r^2$: $F*r^2=k\displaystyle q_{1}q_{2}$ Next we divide by $F$: $r^{2}=k\displaystyle \frac{q_{1}q_{2}}{F}$ Finally, we solve for $r$: $r=\pm\sqrt{k\frac{q_{1}q_{2}}{F}}$