Question

Tìm x biết :

x³ - 8 - ( x - 2 )( x - 12 ) = 0

 

Answer 1

x^3 - 8 - (x - 2)(x - 12) = 0

x^3 - x^2 + 14x - 32 = 0

(x - 2)(x^2 + x + 16) = 0

vì x^2 + x + 16 # 0

=> x - 2 = 0

=> x = 2