Add blank to each side of x^2-8x=9

Step-by-step explanation:

To complete the square, take half of the second coefficient, square it, then add the result to both sides.

(-8/2) ² = (-4) ² = 16

x² - 8x + 16 = 9 + 16

Solving:

(x - 4) ² = 25

x - 4 = ±5

x = 4 ± 5

x = - 1 or 9