x = y^2, what if the value of y - x?

1. x = 4
2. x + y = 2

The answer is C but I got A.

Statement 1 I plugged 4 in for x.
4 = y ^2
Square both sides and got 2.
Therefore, I know that X = 4 and y = 2
If I did that correctly, statement 1 is sufficient
Answers are down to A and D

Statement 2 is not sufficient on its own-- making the answer A.

Where did I go wrong?

Thank you!

from (1)

4 = y^2

so y = 2 or y = -2

y - x = 2 - 4 = - 2 y - x = -2 - 4 = - 6

or

y - x = -2 - 4 = -6 y - x = -6 - 4 = - 10

so (1) is not sufficient


with (1) and (2)

x = 4 and y = 2 - x

so y = 2 - 4 = - 2 y - x = - 2 - 4 = - 6 so (1) and (2) are sufficient


Veritas Help

I got it. Thank you