Question

解方程：x三次方+2x²-x-2=0

Answer 1

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

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

x(x^2+2x+1)-2(x+1)=0

x(x+1)^2-2(x+1)=0

(x+1)[x(x+1)-2]=0

(x+1)(x^2+x-2)=0

(x+1)(x+2)(x-1)=0

x=-1 或x=-2或x=1