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Math Help - basic algebra help!

  1. #1
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    basic algebra help!

    this is a simple question but its confused me
    heres the question

    f(x)= 2 - x^2 where x = -3

    is it -7 or is it 11 im confused by the sign change


    thanks..
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  2. #2
    Junior Member shinhidora's Avatar
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    Quote Originally Posted by mike--1988 View Post
    this is a simple question but its confused me
    heres the question

    f(x)= 2 - x^2 where x = -3

    is it -7 or is it 11 im confused by the sign change


    thanks..
    f(x) = 2 - x^2 where x = -3
    f(x) =  2-(-3)^2
    f(x) = 2 - 9
    f(x) = -7
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  3. #3
    MHF Contributor
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    3(3)=3+3+3=9

    3(-3)=-3-3-3=-9

    (-3)(-3)=-[3(-3)]=opposite\ of\ subtract\ 3\ three\ times

    which\ is\ add\ 3\ three\ times.

    Hence\ (-3)(-3)=3(3)=9

    2-x^2=2-(-3)^2=2-(9)=-7
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  4. #4
    Super Member bigwave's Avatar
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    honolulu
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    Quote Originally Posted by mike--1988 View Post
    this is a simple question but its confused me
    heres the question

    f(x)= 2 - x^2 where x = -3

    is it -7 or is it 11 im confused by the sign change


    thanks..
    f(-3) = 2 -(-3)^2 = -7
    Last edited by bigwave; January 5th 2010 at 09:48 AM. Reason: more info
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  5. #5
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    thanks everyone
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