Answer
$(f\circ g)(x)=-2cot(x)$ and $(g\circ f)(x)=cot(-2x)$.
See graph.
Work Step by Step
1. Given $f(x)=-2x$ and $g(x)=cot(x)$, we have $(f\circ g)(x)=-2cot(x)$ and $(g\circ f)(x)=cot(-2x)$.
2. See graph for $(f\circ g)(x$ (red) and $(g\circ f)(x)$ (blue).