Use eulers formula to write 3+3i^3 in exponential form

What are the possible rational zeros of [tex]f(x) = x^4+2x^3-3x^2-4x+18[/tex]

What is the multiple zero and multiplicity of f(x) = (x ? 3)(x ? 3)(x + 5)? multiple zero is 3; multiplicity is 2 multiple zero is 5; multiplicity is 1 multiple zero is ? 5; multiplicity is 1 multiple zero is ? 3; multiplicity is 2

Me. i can't figure out this question. give an explanation too. .