i don't get it at all

Question

, including factors for irrational zeros. Use radicals, not decimal approximations.

Answer 1

By trial and error, f(3) = 0, so x - 3 is a factor.

Divide f(x) by x - 3 to get f(x) = (x - 3) (x² + 6x + 7)

Now use the quadratic formula to determine the roots of x² + 6x + 7.