Calculus
posted by Mary .
Form a polynomial, f(x) with real coefficients having the given degree and zeros. Degree: 4 ; Zeros: 4i and 5i
Really need help! don't know where to start.

Review the properties of polynomials with real coefficients. If they have complex roots, the roots appear in conjugate pairs. So, since you have roots 4i and 5i, the other roots are 4i and 5i.
Recall that x^2 + a^2 = (xai)(x+ai)
So, your polynomial is (x^2+16)(x^2+25) = x^4 + 41x^2 + 400