Question

X^2-18x+81=4 solve completing the square

Answer 1

x = 7 , x = 11

Explanation:

x² - 18x + 81 = 4 ( subtract 81 from both sides )

x² - 18x = - 77

to complete the square

add ( half the coefficient of the x- term )² to both sides

x² + 2(- 9)x + 81 = - 77 + 81

(x - 9)² = 4 ( take square root of both sides )

x - 9 = ±
`√(4)` = ± 2 ( add 9 to both sides )

x = 9 ± 2

then

x = 9 - 2 = 7

x = 9 + 2 = 11