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Math Help - evaluate expression

  1. #1
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    evaluate expression

    given that f(x) = x^3, evaluate [f(x+h) - f(x)]/h

    don't know even know how to start
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  2. #2
    Super Member Quacky's Avatar
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    Re: evaluate expression

    f(x+h)=(x+h)^3
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  3. #3
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    Re: evaluate expression

    hold, i have to stock up my post count, i cannot view your image
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  4. #4
    Super Member Quacky's Avatar
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    Re: evaluate expression

    What a bothersome irritation, through no fault your own. What I had typed is this:

    f(x+h)=(x+h)^3

    And knowing that f(x)=x^3 means you should just be able to do a direct substitution, no?
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  5. #5
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    Re: evaluate expression

    let me try

    f(x) = x^3

    [(x+h)^3 - x^3] / h

    [x^3 + 3x^2h + 3xh^2 + h^3 - x^3] / h

    [3x^2h + 3xh^2 + h^3] / h

    [h(3x^2 + 3xh + h^2)] / h

    3x^2 + 3xh + h^2

    is this correct? sorry it look very ugly.

    btw off topic; what software you use to type your math formula out, i guess it shouldn't be microsoft office or something since i don't know there's a format for that
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  6. #6
    Super Member Quacky's Avatar
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    Re: evaluate expression

    Yeah, looks good. And I use latex, which is a site feature. The "latex help" subforum will get you used to using and appreciating it.
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