When asked to factor the trinomial x2 - 18x + 81, a student gives the answer (x - 9) (x + 9). Which of the following statements is true?

A. The answer is incorrect; the trinomial cannot be factored.

B. The answer is incorrect; the minus sign should be a plus sign.

C. The answer is incorrect; the plus sign should be a minus sign.

D. The answer is correct.

Question

8 November, 19:07

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Answers (1)

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Benjamin Barton · Answer 1

The answer is C. (X-9) (x+9) equals x^2 - 81. But, (x-9) (x-9) is x^2-18x+81.