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question about QR in topscore.

Discussion in 'DAT Discussions' started by jjw822, Jun 16, 2008.

  1. jjw822

    7+ Year Member

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    I searched past threads and they linked some website which are not existing anymore..lol

    anyway,, topscore test 2 QR #20, which is the third term in the expansion of (x+)^5??

    how would i do this problem???

    I have DAT in this saturday.... i am fricking out...
     
  2. lemoncurry

    lemoncurry tequila mockingbird
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    sounds like a typo to me. what are the answer choices? Seems like they want you to expand a quadratic to the fifth power and give the third term (i.e. to the 3rd power).

    however, it seems it is missing a number. For example, it should be (x+1)^5 or something. In which case, you should multiply it out: (x+1)(x+1)(x+1)(x+1)(x+1)

    (x+1)^2 = x^2 + 2x +1

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

    times (x+1) = x^4 + 4x^3 + 6x^2 + 4x + 1

    times (x+1) = x^5 + 5x^4 + 10x^3 + 10x^2 + 5x + 1

    third term would be 10x^3, if I understand the question correctly.

    If you notice the pattern of the answers, it follows the binomial theorem.

    http://en.wikipedia.org/wiki/Binomial_theorem
     
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  3. jjw822

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    oops
    it is supposed to be (x+3)^5

    and answer choices are

    a. 10x^3
    b. 9x^3
    c. 90x^3
    d. 90x^4
    e. 10x^4
     
  4. jjw822

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  5. DentalDeac

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    [​IMG][​IMG]So using the binomial theorum the answer would by 90x^3, C.
     
  6. jjw822

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    what is that??
     
  7. lemoncurry

    lemoncurry tequila mockingbird
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    You can't do an img tag for a file on your hard drive.
     
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