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Math Help - Multiplying with indices

  1. #1
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    Multiplying with indices

    Hi, Can you see where I have gone wrong with this please?

    Question: Simplify (x+x+2x^2)^3

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

    =(4x^2)^3

    =(4)^3\times(x^2)^3

    =64x^6

    (The book's answer is 27x^6)
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  2. #2
    Member SENTINEL4's Avatar
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    Quote Originally Posted by Meggomumsie View Post
    Hi, Can you see where I have gone wrong with this please?

    Question: Simplify (x+x+2x^2)^3
    then it is = (2x+2x^2)^3 not (4x^2)^3
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  3. #3
    Member SENTINEL4's Avatar
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    Maybe there's an error on what you want?
    I can't get (x+x+2x^2)^3=27x^6

    Maybe it is (x*x+2x^2)^3 ??
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  4. #4
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    Dohh!! Thank you
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  5. #5
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    Thanks Sentinel4 - I have checked in the book and it is

    as you suggested.

    =(x*x+2x^2)^3

    =(x^2+2x^2)^3

    =(3x^2)^3

    =(3*3*3)(x^2)^3

    =27x^6


    Why didn't I see that?
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  6. #6
    Member SENTINEL4's Avatar
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    Read the exercises more carefully. You saw what difference makes a + instead of * ??
    I make this mistake a lot, try to solve it quick, then i realize i forgot a number, a parentheses etc and back to the beginning of the exercise lol
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