Chapter 4 - Inverse, Exponential, and Logarithmic Functions - 4.5 Exponential and Logarithmic Equations - 4.5 Exercises - Page 468: 7

$x=log_7(19)$ $x=\frac{log19}{log7}$ $x=\frac{ln19}{ln7}$

Step 1. For $7^x=19$, use the meaning of logarithm to get $x=log_7(19)$ Step 2. Use the change-of base theorem to write the result of step 1 as $x=\frac{log19}{log7}$ Step 3. Use the change-of base theorem to write the result of step 1 as $x=\frac{ln19}{ln7}$