Appendix A - Review - A.4 Factoring Polynomials - A.4 Assess Your Understanding - Page A40: 119

$(x+2)(x-1)(x+1)$

We factor by grouping as follows $$ x^3 + 2x^2 - x - 2= x^2(x+2)-(x+2) .$$ Now, factoring $x+2$ out, we have $$ x^2(x+2)-(x+2) =(x+2)(x^2-1) .$$ Since $(x^2-1)$ is a difference of two squares, we have $$ (x+2)(x^2-1)=(x+2)(x-1)(x+1) .$$ where we used the formula $(x-y)(x+y)=x^2-y^2$.