Question 996220
x^2-16=-6x
Would I add 6x to both sides? 
Why not?
x^2 + 6x - 16 = 0
Add 16
x^2 + 6x = 16
(b/2)^2 = 9
Add 9
x^2 + 6x + 9 = 25
(x+3)^2 = 5^2
etc