Answer
{$\frac{e^{2}-1}{3}$}, {$2.1297$}
Work Step by Step
Step 1: $\ln (3x+1)=2$
Step 2: $3x+1=e^{2}$
Step 3: $3x=e^{2}-1$
Step 4: $x=\frac{e^{2}-1}{3}\approx2.1297$
Therefore, the exact solution is {$\frac{e^{2}-1}{3}$}. The answer, to four decimal places, is {$2.1297$}.