Equations must be separated by commas. Refer to Input of Functions for proper syntax.
Entering...
y = 2x+1, x = -2, x = 3, y = 1
will draw a "dotted" line with equation y=2x+1, two vertical "dotted" lines at x=-2 and x=3, and a horizontal "dotted" line at y=1. Non-linear asymptotes are also possible.
