Question 139496
x^2 + 16x = 0 

x^2 + 16x + (16/2)^2 = 0 + (16/2)^2

x^2 + 16x + 64 = 64

Factor:

(x+8)^2 = 64

Take the square root of both sides:

x+8 = +8 or x+8 = -8

x = 0 or x = -16
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Cheers,
Stan H.