x² + 10x + 16 = 0
The pattern of a perfect square binomial is a² + 2ab + b². Thus, in this equation, a = x, 2ab = 10x.
2ab = 10x since a = x, dividing both sides with a would cancel them out
2b = 10
b =5
So, our last term must be 5² or 25. But what we have is a 16. So, we must add 9 to both sides of the equation to get 25.
x² + 10x + 16 + 9 = 0 + 9
x² + 10x + 25 = 9
(x + 5)² = 9
x + 5 = +-3
x+5 = 3
x = -2
x+5 = -3
x = -8
