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Math Help - Please help Factor by grouping problem

  1. #1
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    Please help Factor by grouping problem

    Tried posting this elsewhere but running out of time

    2x^3 + x^2 - 2x - 1

    (2x^3 + x^2) + (2x + 1)

    x^2( 2x + 1) + 1(2x + 1) found the common factor(not sure if thats the right term)

    So my final answer would be this which is wrong, anyone got a solution?

    (2x + 1)(x^2 +1)
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  2. #2
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     2x^3 + x^2 - 2x - 1<br />

    x^2(2x + 1) - (2x+1)<br />

    now factor it ...
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  3. #3
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    Close

    You have the right idea. However, when you get to this point:

    (2x^3 + x^2) + (-2x -1)

    you need to factor out a (-1) from the right hand terms. Then you will get:

    x^2(2x + 1) -(2x + 1)

    Therefore your answer is:

    (x^2 - 1)(2x + 1)

    which can also be written as:

    (x + 1)(x - 1)(2x + 1). So (A) would be your answer.
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