Answer
1.9542
Work Step by Step
For all positive numbers $a$, where $a\ne1$, and all positive numbers $x$, we know that $y=log_{a}x$ means the same as $x=a^{y}$.
Therefore, $log(90)=x$ means the same as $10^{x}=90$.
By using a calculator to approximate, we know that $x=1.9542$, because $10^{1.9542}=90$.
Recall that a logarithmic function in the form $log(x)$ is a common logarithm with an understood base of 10.