Posted by phyllys on .
find all the zeros of f(x)=x33x2+4x12

PreCal. 
Steve,
you know that are all factors of 12. A little regrouping shows you have
f(x) = x^33x^2+4x12
= x^2(x3) + 4(x3)
= (x^2+4)(x3)
so, f(x) = 0 at x = 3, ±2i