What number should be added to both sides of the equation to complete the square?

x2 + 8x = 4

a. 4
b. 8
c. 16
d. 32

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.

1. d.90

2. e. none of these (80)

3. a. 0

4. b. 6

5. e. none of these (10)

6. a. 5

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