Evaluate
Please show work
I got that the answer is 4 because 7^{log7} = 1
I would suggest that you start with the definition of the logarthm: If $\displaystyle a^b = c$ then $\displaystyle \log_a c = b$. Here 'a' is 7 and 'b' is $\displaystyle \log_7 4$, therefore from the right hand side of the definition $\displaystyle \log_7 c = b = log_7 4$. Hence c = 4, and $\displaystyle 7^{\log_7 4} = 4$.