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math function cubes & multiple squares

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    math function cubes & multiple squares

    Having a problem putting in a math function into excel speak.

    Here's the math function...

    Y=x³-3x²-x-5
    So, I've got the first part down (let's suppose that 'x' is in A1)...
    =A1+POWER(A1,3)
    It's the 3* that I'm having a problem with
    I've done 3*A1+POWER(A1,2) not right answer
    Done 3*(A1+POWER)(A1,2) not right answer
    HELP!!!!

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    Re: math function cubes & multiple squares

    You can use ^ instead of POWER so this formula should work

    =A1^3-3*A1^2-A1-5
    Audere est facere

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    Re: math function cubes & multiple squares

    I know that I'm supposed to not have to use POWER, but I can't figure out how to do that other symbol on my computer - total newb.

    Can you tell me how? Or can you show me how to do the formula using POWER?

    Thanks!

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    Re: math function cubes & multiple squares

    On my keyboard ^ is on the same key as 6, I don't know if that's the same for you.....otherwise just try

    =POWER(A1,3)-3*POWER(A1,2)-A1-5

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    Smile Re: math function cubes & multiple squares

    Thanks, I will!

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    Question Re: math function cubes & multiple squares

    Tried it, and I get an answer...but not same answer as if I figure it out manually

    Value of x is -10 That formula gives me the answer -875

    If I do it manually, answer is -1295

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    Re: math function cubes & multiple squares

    Highlight the formula in the Excel equation bar and select copy, then select Paste in your new post here to show the actual formula that you entered in the spreadsheet, don't type it in.
    Ben Van Johnson

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    Re: math function cubes & multiple squares

    =A5+power(A5,3)-3*A5+power(A5,2)-A5-5


    remember, original equation was...

    y=x³-3x²-x-5
    Last edited by MelissaBeynon; 10-24-2010 at 09:02 PM. Reason: forgot something

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    Re: math function cubes & multiple squares

    but the 'a' was capitalized...don't know why that didn't transfer in the copy-paste

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    Re: math function cubes & multiple squares

    Please note:
    The formula below (pasted in from your Excel sheet) has six terms
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    Replacing A5 with "x" in your formula and combining like terms results in
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    which is not the equation given in the original post.
    Notice that the first term, A5, cancels the fifth term, -A5

    Then look at your third and forth terms, namely: 3*A5 AND Power(A5,2)

    your intent was to multiply x-squared by three, however you actually multiplied x by three and added x-squared.

    What you wanted was just 3*Power(A5,2) not 3*A5+Power(A5,2)

    Finally, note that all you had to do was copy daddylonglegs
    formula
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    from his post and paste it directly into your spreadsheet cell, replacing A1 with A5.

    Thus:
    =A5+POWER(A5,3)-3*A5+POWER(A5,2)+A5-5 ==> x³-3x+x²-5 ==> -895


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