Answer if you only know this. and you get more

4. A graph shows the solutions to be
  x = -3/2, -1, 0
The root at -1 has multiplicity 2. That is, the factoring is
  x(2x+3)(x +1)² = 0

5. A graph shows the real roots to be
  x = -1, 2
Dividing these from the polynomial gives the quadratic
  x^2 +3
which has roots
  x = ±i√3

The factorization is
  (x +1)(x -2)(x² +3) = 0
and the solutions are
  x = -1, 2, -(√3)i, (√3)i