Answer:
x = -4
Step-by-step explanation:
Subtract x^2-16 from both sides:
x^2 +8x +16 = 0
(x +4)^2 = 0 . . factor
x +4 = 0 . . . . . take the square root
x = -4
The one real solution is x = -4.
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Additional comment
As you can see from the factoring, the root has multiplicity 2.
