The solution of a linear equation in 2 variables, f(x,y) = 0, is a straight line in the x,y plane.
The solution of a linear inequality is EITHER all the points above that line or below it.
To UNsolve a linear equation or inequality, use the a, b and c sliders in the
rightmost panel to fix the solution set. The left panel will show the solution set. The center
panel will show you a linear equation or inequality that has that solution set.
You can use the c slider in the rightmost panel to see other linear
equations or inequalities that have the same solution set.
For a given solution set, how many equations or inequalities are there that
have that solution set? How do you know? Can you prove it?