GMAT Club Tests | M27-02

In case it doesn't strike you to arrange the algebra, you can do the question the following way

St 1 : 4y^2 + 3x^2 = x^4 + y^4

Notice that 4y^2 is always going to be even.
Therefore, whether LHS is even or odd will depend upon the value of x.

If x = even,
then LHS is even. RHS will also have to be even. In RHS, since x is even, y will also be even. (if y is odd, then LHS will not be equal to RHS)

If x = odd,
then LHS is odd. RHS will also have to be odd. In RHS, since x is odd, y will have
...

---