Question

How do you graph `y=x+9`?

Answer 1

Recognize the equation as a straight line;
find two coordinates that satisfy the equation and plot them on a graph;
draw a straight line through those points.

Explanation:

Two simple coordinates for `y=x+9` would be the intercepts:
`color(white)("XXX")(0,9) and (-9,0)`

Plotting these point and drawing a line through them:
graph{(x^2+(y-9)^2-0.02)((x+9)^2+y^2-0.02)(x-y+9)=0 [-12.31, 13, -1.91, 10.75]}