Answer:
x =
2 , 8
Step-by-step explanation:
(x-5)² = (x-5)(x-5) = x*x + x*-5 - 5*x - 5*-5 = x² - 5x - 5x + 25
= x² - 10x + 25
x² - 10x + 25 = 9
x² - 10x + 25 - 9 = 0
x² - 10x + 16 = 0
x = {-(-10)±√((-10)²-(4*1*16))} / (2*1)
x = {10±√(100-64)} / 2
x = {10±√36} / 2
x = {10±6} / 2
x₁ = {10-6} / 2 = 4/2 = 2
x₂ = {10+6} / 2 = 16/2 = 8
Check:
x₁
(2-5)² = 9
-3² = 9
x₂
(8-5)² = 9
3² = 9
