# Is x=y^2 a function?

Jul 13, 2015

No it isn't.

#### Explanation:

A function gives just one $y$ for every $x$.
In this case there will always be two $y$'s for every $x$, because the reverse will be $y = + \sqrt{x} \mathmr{and} y = - \sqrt{x}$

Example: $x = 4 \to y = - 2 \mathmr{and} y = + 2$