# Y as a function of x

1. Oct 12, 2006

### AznBoi

Hmm I'm not sure if this is correct:

Problem: Decide whether the equation represents y as a function of x:

y=sq.rt.(x+3)

Ok, so do square roots always have the plus/minus sign automatically? Radicals are the equivalent of sleep parabolas right?? Do I add the bottom half also??

My answer was No because it is a radical/sleeping parabola.

2. Oct 12, 2006

### HallsofIvy

Staff Emeritus
No, $\sqrt{x}$ is defined as the positive number whose square is equal to x. Square root, like any real valued function, is single valued.

"Sleeping" parabola? You mean a parabola with its axis horizontal?
Unfortunately, you are wrong. $\sqrt{x+3}$ is a function. It's graph is the top half of the horizontal parabola.

3. Oct 12, 2006