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Math Help - [SOLVED] finding inverse formulas

  1. #1
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    [SOLVED] finding inverse formulas

    i can find the inverse of a function, but im having trouble finding the formulas in these problems

    Find a formula for the inverse of the function.
    y = 8x^3 + 7


    Find a formula for the inverse of the function. y = ln(x + 8)
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  2. #2
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    Quote Originally Posted by kyleu03 View Post
    i can find the inverse of a function, but im having trouble finding the formulas in these problems
    Please reply showing what you've tried, so we can "see" where you're "having trouble" and then help you get un-stuck.

    Thank you!
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  3. #3
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    Quote Originally Posted by kyleu03 View Post
    i can find the inverse of a function, but im having trouble finding the formulas in these problems

    Find a formula for the inverse of the function.
    y = 8x^3 + 7


    Find a formula for the inverse of the function. y = ln(x + 8)
    Why don't you apply your knowledge to the first problem? It's not really any different.

     <br /> <br />
y = 8x^3+7<br />
x = 8y^3+7
    x-7 = 8y^3

    Take the cube root.

     y = \sqrt[3]{\frac{(x-7)}{8}<br />
}
    Last edited by A Beautiful Mind; September 29th 2009 at 09:14 AM.
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  4. #4
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    Quote Originally Posted by A Beautiful Mind View Post
    Why don't you apply your knowledge to the first problem? It's not really any different.

     <br /> <br />
y = 8x^3+7<br />
x = 8y^3+7
    x-7 = 8y^3

    Take the cube root.

     y = \sqrt[3]{\frac{(x-7)}{2}<br />
}

    thats wrong...
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  5. #5
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    Quote Originally Posted by kyleu03 View Post
    thats wrong...
    the /2 should be /8

    but thanks
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  6. #6
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    still cant figure out
    y = ln(x + 8)
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