ShmoopTube

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And here's another shmoop du jour... Which of the following is not a factor of

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x cubed minus x?

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And here are the potential answers...

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Okay can we factor?

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Here, the common element on both sides of the minus sign is x.

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If we pull out that x...

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...we get x times the quantity x squared minus 1.

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But now we have x squared minus 1... it's a magic number we should recognize.

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X squared minus 1 is a factorable beast...

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...in quantity x plus 1 times quantity x minus 1.

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So the factors are x... then quantity x plus 1... then quantity x minus 1.

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If we look down our answers list, the only factor left that ISN'T an element of this

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equation is x squared plus 1...

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... so the answer is... E.

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