Question

What value(s) of x make the equation x2 - 18x + 81 = 0 true?

9

-9, 9

0, 9

0, -9, 9

Answer 1

9

Explanation:

x² - 18x + 81 = 0

x² - 9x - 9x + 81 = 0

x(x - 9) - 9(x - 9) = 0

(x - 9)(x - 9) = 0

(x - 9)² = 0

x - 9 = 0

x = 9

Answer 2

x^2 - 18x + 81 = 0
x^2 - 9x - 9x + 81 = 0
x(x - 9) - 9(x - 9) = 0
(x - 9)(x - 9) = 0
(x - 9)^2 = 0
x - 9 = 0
x = 9