text: 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 $\frac{\ln 4 }{7\ln 4}+\ln5 = \frac{1 }{7}+\ln5$