Question

Calcule (x-2).(x+4)=2.(x+4)

Answer 1

(x -2 ) (x+4) = 2 (x+4)
x² + 4x - 2x - 8 = 2x + 8
x² + 2x -8 -8 -2x = 0
x² + 2x - 2x - 16 = 0
x² - 16 = 0
x² = 16
x = √16
x' = 4
x''= - 4

S = {4,-4}