Question

How do you graph `x+y=3`?

Answer 1

Plot two solution points and draw a line through those points.

Explanation:

Since `x+y=3` is a linear equation
we only need two points to plot the equation's line.

Two obvious points to use would be the x and y intercepts:
`color(white)("XXX")(0,3)` and `(3,0)`

Plotting these two points and drawing a line through them should give a graph like:
graph{((x-3)^2+y^2-0.01)(x^2+(y-3)^2-0.01)(x+y-3)=0 [-6.323, 9.48, -2.71, 5.19]}