Answer
$e^x=4$
Work Step by Step
RECALL:
(1) Logarithm is defined as:
$\log_a{x}= y \longleftrightarrow a^y=x$
(2) The natural logarithmic function is $y=\ln{x}$ or $\log_e{x}$
Thus, the exponential equivalent of the given natural logarithmic expression is:
$e^x=4$