3 and -3 are the two zeros of the polynomial (x4+x3−11x2−9x+18)
Therefore, (x–3)(x+3)=x2–9 is a factor of given polynomial
Therefore, Dividing the given polynomial by x2–9
Therefore, Quotient q(x)=x2+x–2
Other zeros of given polynomial are -2 and 1
So zeros of given polynomial are 1, -2,3 and -3