Question

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

Answer 1

The answer is 9x^2-4=y because when you inverse an equation you reverse it.

Answer 2

First swap the x and y variable, then isolate y.

y = 9x^2 - 4
x = 9y^2 - 4
x + 4 = 9y^2
(x+4)/9 = y^2

plus or minus
$\sqrt{((x + 4) \div 9} = y$