Answer
$x=-\log4\approx-0.602060$
Work Step by Step
$10^{-x}=4$
We apply $\log$ to both sides of the equation:
$\log10^{-x}=\log4$
$-x$ can be taken down to multiply in front of the logarithm:
$-x\log10=\log4$
Since $\log10=1$, the solution to this equation is:
$-x=\log4$
$x=-\log4\approx-0.602060$
