SOLUTION: Write. Polynomial function with rational coefficient in standard form with the given zeros x=3+i,2-i

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Question 868265: Write. Polynomial function with rational coefficient in standard form with the given zeros x=3+i,2-i
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
If a polynomial with rational coefficients has a non-real zero, it must also have the conjugate non-real zero.
That is to say that if 3%2Bi is a zero, 3-i must be a zero too.
That means that the factorization of the polynomial must contain the factors
x-%283%2Bi%29=x-3-i=%28x-3%29-i and x-%283-i%29=%28x-3%29%2Bi .
So the polynomial must have as a factor
.
The same applied to the zero 2-i means that
x-%282-i%29=x-2%2Bi=%28x-2%29%2Bi and x-%282%2Bi%29=x-2-i=%28x-2%29-i area factors,
and the polynomial must have as a factor
.
In sum, the polynomial must have for a factor
%28x%5E2-6x%2B10%29%28x%5E2-4x%2B5%29=x%5E4-10x%5E3%2B39x%5E2-70x%2B50 .
The simplest answer would be
highlight%28f%28x%29=x%5E4-10x%5E3%2B39x%5E2-70x%2B50%29 .
Of course, multiplying that polynomial by any rational number we can get another answer,
like g%28x%29=3x%5E4-30x%5E3%2B117x%5E2-210x%2B150 ,
or g%28x%29=%282%2F3%29x%5E4-%2820%2F3%29x%5E3%2B26x%5E2-%28140%2F3%29x%2B100%2F3 .