Question

Which equation represents a function?

y2 + x = 6

y4 + x3 = 3

y – x2 = 4

y2 – x2 = 7

y2 + x2 = 7

Answer 1

I believe the fisrt one but I dojnt know if im right

Answer 2

no y - x2 = 4 is not a function
because some values of map to more that 1 value of x
for example
y = x2 + 4

when y = 8 x can be 2 or -2

Answer 3

Yes its the first one because for each value of y there is only one value of x