# Math Help - exponential functions

1. ## exponential functions

I'm having trouble with the following:

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

2. 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?

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