If the image vertex of the quadratic function y = 2x2 + 4x + C is on the X axis, what is C equal to …………

If the image vertex of the quadratic function y = 2x2 + 4x + C is on the X axis, what is C equal to …………

Method 1)
y=2x²+4x+c=2(x²+2x)+c=2(x+1)²+c-2
So C-2 = 0, that is, C = 2
Method 2)
Discriminant
=△
=b^2-4ac
=16-4×2c=0,
The solution is C = 2