Find Polynomial Equation: 3 Zeros, f(2)=91

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Homework Help Overview

The discussion revolves around finding a polynomial equation given specific zeros and a value of the polynomial at a certain point. The subject area includes polynomial functions and complex numbers.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants explore the implications of the given zeros, including the necessity of complex conjugate pairs. Questions arise regarding the degree of the polynomial and the nature of its coefficients.

Discussion Status

Some participants have suggested a polynomial form based on the zeros and are attempting to determine the leading coefficient. There is an ongoing exploration of assumptions regarding the coefficients being real, and some confusion exists about the implications of the initial condition provided.

Contextual Notes

Participants note that the problem may involve assumptions about the nature of the coefficients and the completeness of the information provided to determine the polynomial uniquely.

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I need to find the polynomial equation. The givens are: n=3; -5 and 4+3i are zeros; f(2)=91
I have no idea how to find this? Can you please help
 
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is n the degree of the polynomial?

Hint: if 4+3i is a zero, then 4-3i is a zero.

So you know that your polynomial is of the form c*(x+5)(x-4-3i)(x-4+3i), where c is some constant.

Now you need to figure out what c is.
 
grief is also assuming that all coefficients are real numbers. It is also possible to have a polynomial with complex coefficients but then the information given would not be enough to determine the polynomial.
 
"grief is also assuming that all coefficients are real numbers. It is also possible to have a polynomial with complex coefficients but then the information given would not be enough to determine the polynomial."

I must be misunderstanding: both by hand and with Scilab I obtain specific real and complex parts for a polynomial that has the o.p.'s specifications (zeros and value for x = 0). It would seem that the "initial condition" nails down the leading coefficient, and the factors that correspond to the zeros do the rest.

I've been grading all afternoon, so am rather zonked. What simple thing am I missing?
 

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