SOLUTION: Use cases to prove that x^2+x-1=0 has no rational solutions.

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Question 362883: Use cases to prove that x^2+x-1=0 has no rational solutions.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
By the rational roots theorem, if the equation has rational roots, they are of the form,
x=1%2F1 or x=-1%2F1
For x=1,
1%5E2%2B1-1=1%2B0=1 so that is not a solution.
For x=-1,
1%5E2-1-1=1-2=-1 so that is not a solution.
So there are no rational roots.
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graph%28300%2C300%2C-3%2C3%2C-3%2C3%2Cx%5E2%2Bx-1%29