# Math Help - Evaluate a logarithmic function

1. ## Evaluate a logarithmic function

Evaluate

I would suggest that you start with the definition of the logarthm: If $a^b = c$ then $\log_a c = b$. Here 'a' is 7 and 'b' is $\log_7 4$, therefore from the right hand side of the definition $\log_7 c = b = log_7 4$. Hence c = 4, and $7^{\log_7 4} = 4$.