Which are real zeroes of this function? x3 + 2x2 – 9x – 18

The real zeroes of this function  are: -2,-3 and +3

By hit and trial method, we find that x = -2 will the root of this polynomial.

We do the factorisation of the given polynomial:
\\ \\ " alt="(x+2) = 0 \\ and \\ (x^{2} -9)=0 \\ \\ x= -2 \\ and \\ x = +3,-3" /> \\ \\ " />