## Homework Statement

Solve the equation for x

$y^2 = 4x$

$x^2 = 4y$

None

## The Attempt at a Solution

$y^2 -4x = x^2 - 4y = 0$

I have spent ages re-arranging and substituting in values but I just cannot solve this thing.

CAF123
Gold Member
Why don't you try to rearrange the second equation for y and sub into the first equation. This will give you an equation entirely in terms of x.

$y = 2\sqrt{x}$
$y = \frac{x^{2}}{4}$

I still have no idea how to find $x$

Mark44
Mentor
$y = 2\sqrt{x}$
$y = \frac{x^{2}}{4}$

I still have no idea how to find $x$

You didn't do what CAF123 suggested, which was to solve for y in the second equation, and then substitute for y in the first equation.

You solved for y in the second equation, but then solved for y (incorrectly) in the first equation. Note that if y2 = 4x, then y = 2√x is only one of two solutions.