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Math Help - exponential functions

  1. #1
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    exponential functions

    I'm having trouble with the following:

    exponential functions-expo-fx.png

    i cannot find a problem similar in my book and my friend is stump too. there is an option for no solution.
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  2. #2
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    Can i suggest

     4^{1-7x}= 5^{x}

     \ln 4^{1-7x}= \ln 5^{x}

     (1-7x)\ln 4= x\ln 5

     \ln 4-7x\ln 4= x\ln 5

     \ln 4= x\ln 5+7x\ln 4

     \ln 4= x(\ln 5+7\ln 4)

    can you finish it?
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  3. #3
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    yeah it's very helpful!

    my ans:

    ln4 / 7ln4 + ln5
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  4. #4
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    be careful with how you write your answer

    ln4 / 7ln4 + ln5 could imply only \frac{\ln 4 }{7\ln 4}+\ln5 = \frac{1 }{7}+\ln5

    To stop any confusion use brackets like this ln4 / (7ln4 + ln5)
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