Question

How do you know which relation is NOT a function? (How do you determine or figure that out)

1.) y=2x+4
2.) y=x^2-4x+3
3.) x=3y-2
4.) x=y^2+2x-3

Answer 1

As written, each is a function.

Now, if you want to check whether y is a function of x, just check to be sure that for each x value there is a single y which satisfies the equation.

hint: (-3)^2 = (+3)^2 for example