What is the inverse of a base 10 logarithm? It should be an exponential, but what does the function of that exponential look like? To determine the exact inverse of a base 10 log, we reflect the function f(x)=log_10(x) across the line y=x (because reflecting across this line generally gives us the inverse of a function). Now we just need to change the value of b to match g(x) with the reflected f'(x) to see what the inverse of a base 10 logarithm function is.