to get the inverse of any expression, start off by doing a switcharoo on the variables.
[tex]\bf y=5x^2+10\qquad inverse\implies \boxed{x}=5\boxed{y}^2+10
\\\\\\
x-10=5y^2\implies \cfrac{x-10}{5}=y^2\implies \sqrt{\cfrac{x-10}{5}}=y\impliedby f^{-1}(x)[/tex]
