Question

quanto é (3x+1) + (x-2) (x+1)= -1

Answer 1

$(3x+1) + (x-2) (x+1)= -1 \\ \\ 3x+1+x^2+x-2x-2+1=0 \\ \\ x^2+2x=0 \\ \\ x(x+2)=0 \\ \\ x_1=0 \\ \\ x_2=-2$

Answer 2

(3x+1) + (x-2) (x+1)= -1
3x +1 +x² +x -2x -2 = -1
x² +3x +x -2x +1 +1 -2=0
x² +4x -2x +2 -2=0     cancela +2 e -2, pois são iguais e sinais diferentes
x² +2x=0
x(x +2)=0
x=0
(x+2)=0
x+2=0
x= -2

S{ 0 ; -2}