To make a perfect square trinomial you take the "b" and divide it by 2, square that value, and add it to the expression. This will make a perfect square trinomial.
b = 4 so..... 4/2 = 2 2^2 = 4 add 4 to the expression x^2 + 4x + 4 = (x + 2) ^2 LETTER D
