Rational Roots of a Polynomial
Rational Roots of a Polynomial
Let be a polynomial with integer coefficients and constant coefficient ≠0. Use this Demonstration to find the rational roots of .
P(x)=++⋯+x+
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Each rational root is of the form , where and are integers such that divides and divides , the leading term. Make a list of all the possible rational roots by considering divisors of and .
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At the start, the set of rational roots found is empty. Choose a candidate from the list. Using the Ruffini–Horner algorithm, divide by to get a polynomial and remainder (cyan box). If , then , and is a root of ; add to . Repeat this process with and the next candidate; continue until all the rational roots have been found. (The maximum number of roots is , so there may be no need to test all the candidates.)
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R=0
P(x)=Q(x)(x-h)
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P(x)/(x-h)
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When =1, the rational roots are integers.
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