Answer:
(x + 8)² = 36
Explanation:
When you are trying to complete the square and the equation already has a constant, you add or subtract that value to the other side of the equation so you can cancel it out.
x² + 16x + 28 = 0
x² + 16x + 28 - 28 = 0 -28
x² + 16x = -28
Now, you find (
)² (divide b by 2 and raise the quotient to the second power). Half of 16 is 8, and 8² is 64. Add 64 to both sides.
x² + 16x + 64 = -28 + 64
x² + 16x + 64 = 36
Now, you just factor the equation on the left. To factor it, you will always use the number you got to make the constant, which in this case is 8.
(x + 8)² = 36