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Math Help - Equation and inverse function problems

  1. #1
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    Equation and inverse function problems

    solve for:

    9^x -5 x 3^x +6= 0

    i've been trying to solve for this in which i have let U equal 3x and then by using the null factor law work out the answer. but somehow i didn't get the right answer :L

    and also for:

    Find the inverse function of

    y=loge (x + 1) -2

    in which i did

    x= loge (y +1 ) -2

    then x -2 = loge ( y+1)

    but i seemed to get the wrong answer.


    any help would be greatly appreciated!!
    Last edited by CaptainBlack; August 5th 2011 at 09:04 PM. Reason: try to give thread informative title
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  2. #2
    Senior Member abhishekkgp's Avatar
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    Re: need help with math questions

    Quote Originally Posted by kiimberly2 View Post
    solve for:

    9^x -5 x 3^x +6= 0


    i've been trying to solve for this in which i have let U equal 3x and then by using the null factor law work out the answer. but somehow i didn't get the right answer :L

    and also for:

    Find the inverse function of

    y=loge (x + 1) -2

    in which i did

    x= loge (y +1 ) -2

    then x -2 = loge ( y+1)

    but i seemed to get the wrong answer.


    any help would be greatly appreciated!!
    for the first one take 3^x=y. Then 9^x=y^2. Your problem boils down to solving a quadratic.
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  3. #3
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    Re: need help with math questions

    Find the inverse function of

    y=loge (x + 1) -2

    in which i did

    x= loge (y +1 ) -2

    then x +2 = loge ( y+1)

    but i seemed to get the wrong answer.


    any help would be greatly appreciated!!
    You're almost there after making the change shown in the quote. Solve this equation for y.
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  4. #4
    MHF Contributor Siron's Avatar
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    Re: need help with math questions

    Notice the logarithmic function is the inverse function of the exponential function.
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