Sorry for the bad title, as English is not my main language. Let me explain better what I mean.
I have this equation of parabola: $y = x^2 + 4x $
What I want to do is get the $x$ in one side and express it in relation to $y$ so that the equation takes this form:
$x = g(y)$
How do I proceed doing that?
just add 4 on both sides
$y+4=x^2+4x+4$
$\implies (y+4)=(x+2)^2$
$\implies (x+2)=(y+4)^{1/2}$
$\implies x=(y+4)^{1/2}-2$