Use mathematical induction to prove the property for all integers $n \geq 1$.
If $x_{1} \neq 0, x_{2} \neq 0, \ldots, x_{n} \neq 0,$ then$\left(x_{1} x_{2} x_{3} \cdot \cdot \cdot x_{n}\right)^{-1}=x_{1}^{-1} x_{2}^{-1} x_{3}^{-1} \cdot \cdot\cdot x_{n}^{-1}$