Lesson goal: Graphing inequalities on the x-axis

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In math class, sometimes you are asked to graph an inequality along a number line. Problems are often stated like "Graph $|x|>2$" or "Sketch $|x+2|<5$." These problems are often quite difficult and involve getting some logic of absolute values ironed out.

Turns out, they are a snap to solve on the computer using a for-loop, if statement, and some simple graphics using pset. Here's how this will work. We'll clear the screen, and draw the xy-coordinate grid in a white color. Then we'll select 1000 random values for $x$ between -250 and 250 (the width of the plotting screen). The if statement asks if the inequality is true..if so, we'll draw a small circle at the random $x$ coordinate chosen. The resulting graph will be the graphed inequality! Wow!

Now you try. Put some inequality relation in between the if and then. Try math.abs(x) > 20 to graph $|x|>20$. When the plot is finished, you can investigate it using the mouse pointer and the x,y coordinates over which you move it.

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