Find the parametric equation of the following parabola?

Question

It doesn't give me $2$ equations this time just $1$ and I have no clue what to do;

$y^2 = 4x$

ANSWER IN BOOK: $x = t^2, y = 2t$

Answer 1

Let $y=s$, put it into equation $y^2=4x$, you get:

$$s^2=4x$$

So:

$$x=\frac{s^2}{4}$$

You have parametric equation $x=\frac{s^2}{4}, y=s$. If you put $s=2t$ you get the same as in answer book.