# What is the focus of the parabola x=y^2 + 4?

This is a parabola 'on its side', opening to the right, rather than the $' y = {x}^{2} + b '$ shape we're more used to. In this case, the focus is at $y = 0$, so it's just $x = 4$.
The focus of this parabola will be at $y = 0$. If we substitute this in to the equation, we get:
$x = {y}^{2} + 4 \to x = {0}^{2} + 4 \to x = 4$