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Math Help - Functions

  1. #1
    EmG
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    Functions

    Anyone know this one?

    f(x)=9x^3-48x^2+64x
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  2. #2
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    Quote Originally Posted by EmG View Post
    Anyone know this one?

    f(x)=9x^3-48x^2+64x
    hello
    factorize with x.
    x(9x^{2}-48x+64)=x(8-3x)^{2}
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  3. #3
    EmG
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    I did and when I did it I get stuck at f(x)=x(9x^2-48x+64)
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    Quote Originally Posted by EmG View Post
    I did and when I did it I get stuck at f(x)=x(9x^2-48x+64)
    9x^2-48x+64=(3x)^2-48x+8^2
    is it clear now ?

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  5. #5
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    Remember !
    (a-b)^2=a^2-2ab+b^2
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  6. #6
    EmG
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    Ummm.. Sadly I do not understand it very well or how to get the zeros from it algebraically.
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  7. #7
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    Quote Originally Posted by EmG View Post
    Ummm.. Sadly I do not understand it very well or how to get the zeros from it algebraically.
    okay..
    do you agree that f(x)=x(8-3x)^{2}
    if yes,all you have to do is to put f(x)=0 and find the solutions.
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  8. #8
    EmG
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    When I pluged it in I got 0=9 so would that mean that there is no zeros in the equation?
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  9. #9
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    Quote Originally Posted by EmG View Post
    When I pluged it in I got 0=9 so would that mean that there is no zeros in the equation?
    f(x)=0\Leftrightarrow x(8-3x^2)=0
    therefore the solutions are \left [ x=0,x=\frac{8}{3} \right ].
    hope that helps.
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  10. #10
    Flow Master
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    Quote Originally Posted by EmG View Post
    When I pluged it in I got 0=9 so would that mean that there is no zeros in the equation?
    Go back and review the basic theory that is undoubtedly given in your classnotes or textbook. You're expected to know that

    f(x)=0 \Rightarrow x(8-3x^2)=0 \Rightarrow x = 0 \, \text{or} \, 8 - 3x^2 = 0 \Rightarrow x = ....
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