Question

x ² + x = 0 ( segundo grau )

Answer 1

x ² + x = 0
x ( x + 1) = 0

x = 0

x + 1 = 0
x = - 1

S = { - 1 ; 0 }

Answer 2

x( x + 1) = 0 
 x = 0
x + 1= 0 
x = -1
S= { 0, -1}