Understanding Absolute Value in Algebra: |x|=+-x Explained

[CompuChip]

Anyone knows who was the "genius" who came up with that anyway?

Probably a genius to whom functions were one-to-one and non-injective functions weren't functions at all, or something like that :tongue2:

 

[HallsofIvy]

Probably a genius to whom functions were one-to-one and non-injective functions weren't functions at all, or something like that :tongue2:

No, "one-to-one" has nothing to do with being a function. f(x)= x² is not one-to-one but is a function. It has everything to do with being "well defined"- for a given value of x, you get a specific, "well defined" value of f(x).

I've always thought of it as similar to what we demand of experiments- if two people do it in exactly the same way, they get the same result.