SOLUTION: How is x-5 a factor of the polynomial x^2-x-20? I know that x-5 is the answer but I have no idea how to do this. Thanks for your help, Sarah

SOLUTION: How is x-5 a factor of the polynomial x^2-x-20? I know that x-5 is the answer but I have no idea how to do this. Thanks for your help, Sarah

Algebra.Com

Question 436468: How is x-5 a factor of the polynomial x^2-x-20? I know that x-5 is the answer but I have no idea how to do this.
Thanks for your help,
Sarah
Answer by robertb(5830) (Show Source): You can put this solution on YOUR website!
Solve x - 5 = 0, or x = 5. Then substitute into the equation:
, so 5 is a root. Then by the factor theorem (if a is a root then x - a is a factor), x - 5 is a factor.
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