Answer
$x \approx 0.59$
Work Step by Step
The base in the exponential equation is 10, so take the common logarithm on both sides to obtain
$\log{10^x} = \log{3.91}.$
Use the inverse property $\log{10^x} =x$ on the left side of the equation to obtain
$x = \log{3.91}.$
Use a calculator and round-off the answer to two decimal places to obtain
$x \approx 0.59.$
