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September 19, 2014

September 19, 2014

Posted by **Mary** on Thursday, September 22, 2011 at 7:53pm.

Really need help! don't know where to start.

- Calculus -
**Steve**, Friday, September 23, 2011 at 1:14pmReview 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 = (x-ai)(x+ai)

So, your polynomial is (x^2+16)(x^2+25) = x^4 + 41x^2 + 400

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