Fill in the blank with a constant, so that the resulting quadratic expression is the square of a binomial.
x^2 + 8x + ____ + 3x^2 + 2x
x^2 + 8x + ____ + 3x^2 + 2x condense
4x^2 + 10x + _____
4 (x^2 + 2.5x) + ____
4 (x + 1.25)^2
4x^2 +10x + 25/4 = (2x +2.5)^2