Question

Which equation is the inverse of y = 9x^2 - 4?

Answer 1

Keep in mind that, to get the inverse expression of any relation, we start off by doing a quick switcharoo on the variables, and then solve for "y", so let's do so,

$\bf y=9x^2-4\qquad \stackrel{inverse}{\boxed{x}=9\boxed{y}^2-4}\implies x+4=9y^2 \\\\\\ \cfrac{x+4}{9}=y^2\implies \sqrt{\cfrac{x+4}{9}}=\stackrel{f^{-1}(x)}{y}$