posted by Terri .
Could someone please explain to me why the line x=4 is a vertical line.
Because x has to be 4 while y can be anything. A vertical line through (4,0)contains all points for which x=4.
Pick any two ordered pairs that satisfy the equation, remember all it said was x = 4
how about (4,0) and (4,5) ? Do they satisfy our condition that x = 4 ?
Plot the points and draw the line.