Question

How do you graph the line `x+4y=4`?

Answer 1

Select at least two sets of coordinates that satisfy the given equation;
plot these points;
draw a line through the points.

Explanation:

Given the equation `x+4y=4`

Its is probably easiest to find values of `x` for a few simple values of `y`

#{: (underline(y),rarr,underline(x)), (0,rarr,4), (1,rarr,0), (2,rarr,-4) :}#
so we have coordinate points:
`color(white)("XXX")(x,y) in {(4,0), (0,1), (-4,2)}`

Plotting these coordinates and drawing a line through them:
graph{((x-4)^2+y^2-0.02)(x^2+(y-1)^2-0.02)((x+4)^2+(y-2)^2-0.02)(x+4y-4)=0 [-7.023, 7.024, -3.51, 3.513]}

Note that two coordinates would have been sufficient but use of at least three helps ensure no accidental errors.