Why is the square root function y=srtx only positive for y?

Question

terenzreignz · Answer

Why indeed :3
$$\Large y = \sqrt{x}$$

terenzreignz · Answer

After all, if you want a number, which, when squared, say, gives 16, you can get either 4 or -4 right?

anonymous · Answer

Yes hahaha

terenzreignz · Answer

It all goes back to the definition of a function :)

terenzreignz · Answer

$$\huge \color{blue}y = f(\color{red}x)$$

terenzreignz · Answer

Remember that for every x that you plug into a function, there MUST be only ONE value of y that comes out...

x are 'inputs', y are 'outputs' and for every input, there must be EXACTLY one output for it to be a function :)

terenzreignz · Answer

So as for$$\Large \color{blue}y = \sqrt{\color{red}x}$$ well, it won't BE a function if we allow y to take negative as well as positive values. Hence only positive ^_^

anonymous · Answer

:) thankss mann. Lots of help

unklerhaukus · Answer

vertical line test