2. Given the lines $l_{1}: y=x, l_{2}: y=2 x$, then the slope of the line $l$ that forms equal angles with $l_{1}, l_{2}$ is
Let the slope of line $l$ be $k$, then $\frac{k-1}{1+k}=\frac{2-k}{1+2 k} \Rightarrow (2 k+1)(k-1)+(k+1)(k-2)=0$ $\Rightarrow 3 k^{2}-2 k-3=0 \Rightarrow k=\frac{2 \pm \sqrt{4+36}}{6}=\frac{1 \pm \sqrt{10}}{3}$.