## Precalculus (10th Edition)

$\approx2.124$
Using the Change-of-Base Formula we know that $\log_a{b}=\frac{\log_c{b}}{\log_c{a}}$. Evaluate the given expression using a calculator to obtain: $\log_4{19}=\frac{\ln{19}}{\ln{4}}=2.12396\approx2.124.$