Math Help Forum: Solving functions

  1. October 25th, 2010, 09:49 AM #1
    Natasha1
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    Solving functions

    How do you go and answer this, need help please...

    Given
    f(x) = xsquared
    g(x) = 2x + 3

    Solve fg(x) = f(x)
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  3. October 25th, 2010, 09:55 AM #2
    Also sprach Zarathustra
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    f(g(x))=(2x+3)^2=x^2=f(x)

    4x^2+12x+9=x^2

    3x^2+12x+9=0

    x^2+4x+3=0

    .
    .
    .
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  4. October 25th, 2010, 10:05 AM #3
    Natasha1
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    Thanks I understand up to 3x^2+12x+9=0 but don't understand why you wrote x^2+4x+3=0 afterwards?
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  5. October 25th, 2010, 10:10 AM #4
    Also sprach Zarathustra
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    Quote Originally Posted by Natasha1 View Post
    Thanks I understand up to 3x^2+12x+9=0 but don't understand why you wrote x^2+4x+3=0 afterwards?
    I divided all by 3...
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  6. October 25th, 2010, 10:12 AM #5
    Natasha1
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    Oh yes of course thanks!
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