$x^2=100,(x\in ℝ)$

$x=\pm \sqrt{100}$

$x_1=10$, $x_2=-10$

$x^{-1}=100,x\in ℝ$

$x^{-1}={\displaystyle \frac{1}{x}}$

${\displaystyle \frac{1}{x}}=100$

$x={\displaystyle \frac{1}{100}}$