1) x 2 (x + 2)(x - 5) = 0 2) (x 2 + 9)(x 2 + 6) = 0

3) f (x) = x 3 + 2x 2 - 8x

4) f (x) = x 3 + 2x 2 - 3x

5) f (x) = x 4 + 5x 3 + 4x 2 + 20x

6) f (x) = x 4 - 8x

State the number of complex roots and the possible number of real and imaginary roots for each equation. Then find all roots.