Question

f(x)= x^3 - 2x^2 - 21x - 18

all possible rational zeros
# of possible positive zeros
# of possible negative zeros
find all the real zeros

Answer 1

rational zeros (plus or minus)
1,2,3,6,18

By Descartes' Rule of Signs,
1 positive root
2 or 0 negative roots

a little synthetic division yields

f(x) = (x+1)(x+3)(x-6)