2022 AMC 12A Problem 21
Problem 21 of 25HarderAlgebra
Let Which of the following polynomials divides
Answer choices
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Solution
If is a root of a divisor, then is required.
The roots of are the primitive th roots of unity, so Reducing exponents modulo and giving Here is a primitive cube root of unity, so this equals
The other four options fail: substituting their roots yields nonzero values (for instance, the primitive cube roots of unity give ).
Thus, the correct answer is E.