What value of c makes x2 + 6x + c a perfect square trinomial? c = if x2 + 6x + c = (x + d)2, then d = .

If x2 + 6x + c = (x + d)2, then d =What value of c makes x2 + 6x + c a perfect square trinomial? c = 

Divide the x-term coefficient by 2: 6/2 = 3
Now square 3: 3^2 = 9
c = 9

If x^2 + 6x + c = (x + d)^2, then d =

x^2 + 6x + 9 = (x + 3)^2 = (x + d)^2, so d = 3