# Graphing Inequalities, Vertical line boundary

Hi,

I am trying to have the CL read an inequality based on manipulating points on the graph. Its still a work in progress, but I’ve gotten pretty far.

I am struggling with inequalities where the boundary is a vertical line. I have a moveable black point that determines which way the inequality shades, and a green point that determines whether it is strict or not. When I move the the black point and the boundary line is x=0 or x=-1 for example the inequality in the note displays as x>0 when it should be x<0.

I know the problem is in the note definition n_01 or n_02, not sure how to fix it, help would be greatly appreciated, this forum is so helpful and I am very thankful! I’ve linked the activity. Graphing Inequalities • Activity Builder by Desmos

I fixed it, it works now!

On screen 1, the dashed line disappears in some cases. I think there was an easier solution, where you could just use a general form of the equation of a line (`(y-y1)(x2-x1)=(y2-y1)(x-x1)` instead of `y=(y2-y1)/(x2-x1)(x-x1)+y1`). That would allow you to ditch most of the extra equations you added for the edge cases. See screen 1 of [Copy of] Graphing Inequalities • Activity Builder by Desmos

1 Like