I need math help. PLEASE PLEASE PLEASE HELP ME!!!?

Question

Determine whether y is a function of x. And please tell me how you got your answer:

1. x^2 + y^2 = 4

2. x^2 + y = 4

*** x^2 means x is squared and y^2 means y is squared.***

Answer 1

i cant remember how to do it algebraically but if you type the equation in a TI-83 calc and graph it you can do the vertical line test...sorry

Answer 2

I'm not sure this is right lol but

x=2

y=0

so x^2 (2^2=4) + y^2 (0^2=0) -------------->4+0 = 4

and x^2 (2^2) + 0 -------------->4+0 = 4