Missing last term for perfect trinomial square

Question

x² + 4 + ____

Answer 1

x² + 4x + _____

To complete the square, take the coefficient of x (which is 4)

and divide that coefficient by 2 (which is 4/2 = 2)

and then square it (which is 2² = 4).

x² + 4x + (4/2)²

x² + 4x + 4

(x + 2)²