Answer: C) 16
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Step-by-step explanation:
The number to the left of the x term is 8. So the x coefficient is 8.
Take half of this value to get 8/2 = 4
Then square that result: 4^2 = 16
Therefore we add 16 to both sides to help complete the square
x^2 + 8x = 4
x^2 + 8x + 16 = 4 + 16 .... add 16 to both sides
x^2 + 8x + 16 = 20
(x + 4)^2 = 20 .... factor the left side
After this point we would apply the square root method and subtract 4 from both sides to get the two roots for x.