Opposite in effect. ${\displaystyle -5}$ is the additive inverse of ${\displaystyle 5}$, because their sum is zero. ${\displaystyle \frac{1}{3}}$ is the multiplicative inverse of ${\displaystyle 3}$, because their product is ${\displaystyle 1}$. For rules on find the inverse of a function, enter 'finding the inverse' into Mathway.