SOLUTION: Determine a polynomial function of lowest degree with rational coefficients that has the following zeros: 1-square root of 5

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Question 1024975: Determine a polynomial function of lowest degree with rational coefficients that has the following zeros: 1-square root of 5
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
You need the conjugate to be a root to get rational coefficients.
y=%28x-%281-sqrt%285%29%29%29%28x-%281%2Bsqrt%285%29%29%29
y=x%5E2-2x-4
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You could also working "completing the square" backwards,
x=1+%2B-+sqrt%285%29
x-1=0+%2B-+sqrt%285%29
%28x-1%29%5E2=5
x%5E2-2x%2B1=5
x%5E2-2x-4=0
y=x%5E2-2x-4