set equal to 0
[tex]0=x^4-x^3-2x^2[/tex]
factor out the [tex]x^2[/tex]
[tex]0=(x^2)(x^2-x-2)[/tex]
what 2 numbers multiply to get -2 and add to get -1? -2 and 1
[tex]0=(x^2)(x-2)(x+1)[/tex]
set each equal to 0
[tex]0=x^2[/tex]
x=0
x-2=0
x=2
x+1=0
x=-1
so the zeroes of the function are at x=-1, 0, 2
