Question

How do you graph `2x-y=4`?

Answer 1

Calculate a few coordinate points that satisfy the given equation;
plot those points;
draw a line through the plotted points.

Explanation:

Given `2x-y=4`

And picking some (arbitrary) `x` values (`x in {0,1,2}`)

We can solve for `y` using these values of `x`
#{: (underline(x),,underline(y)), (0,rarr,-4), (1,rarr,-2), (2,rarr,0) :}#

which provides the coordinates `(x,y) in {(0,-4), (1,-2), (2,0)}`

Plotting these points and drawing a line through them:
graph{(x^2+(y+4)^2-0.02)((x-1)^2+(y+2)^2-0.02)((x-2)^2+y^2-0.02)(2x-y-4)=0 [-6.784, 9.02, -5.576, 2.33]}