Question

x³ + 9x² + 27x + 27 = 0

Answer 1

x³ + 9x² + 27x + 27 = 0

<=> x² + 3.3.x² + 3.3².x + 3³ = 0

<=> (x + 3)³ = 0

<=> x + 3 = 0

<=> x = -3

Answer 2

x³ + 9x² + 27x +27 = 0

=> x³ + 3.x².3 + 3.x.3² + 3³ = 0

=>( x + 3)³ = 0

=> x + 3 = 0

=> x = -3

Vậy x = -3