Functions Modeling Change: A Preparation for Calculus, 5th Edition

$\log a$ asks for the solution to $\log a = 10^?$ with "$?$" being the result. $\ln a$ asks for the solution to $\log a = e^{?}$ with "$?$" being the result. These are two different arguments, so $\log a \ne \ln a$ and the statement must be false.