How to graph 2 x + y = 0 ?

The equation appears to be a straight line, as can be seen. Also that
To draw a straight line, just need two points.
However, it is advisable to have three points so that error, if any, while calculating two points on the lines can be cross checked.
For ${\displaystyle x=0}$, we obtain ${\displaystyle y=0}$, so origin is a point on the line.
For ${\displaystyle x=5}$, we obtain ${\displaystyle y=-10}$, so next point is ${\displaystyle (5,-10)}$
For ${\displaystyle x=-5}$, we obtain ${\displaystyle y=10}$, another point is ${\displaystyle (-5,10)}$
Plotting these points we get the graph
graph{2x+y=0 [-20, 20, -10, 10]}