So basically I have been given two roots of 2+i and 3. It asks what the cubic polynomial is, and sadly I have forgotten how to do this all together. Thanks in advance.
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If one root is (2 + i) then other root must be (2 - i) because the complex roots always occur in conjugate-pairs.
So, the three roots are (2 + i), (2 - i) and 3.
so, the cubic equation is
Please see attached graph.
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