Question

(x² - 9 ) ( x³ + 8 ) = 0

Answer 1

=>(x-3)(x+3)(x+2)=0

hay \(x\in\left\{3;-3;-2\right\}\)

Answer 2

(x² - 9 ) ( x³ + 8 ) = 0
x² - 9 = 0 hay x³ + 8 = 0
TH1 : x² - 9 = 0
          => x²  = 9
          =>      = 3
TH2 : x³ + 8 = 0
          => x³   = -8
          => x    = 2