Answer:

Graphing Systems of Linear Inequalities

To graph a linear inequality in two variables (say, x and y ), first get y alone on one side. Then consider the related equation obtained by changing the inequality sign to an equality sign. The graph of this equation is a line.

If the inequality is strict ( < or > ), graph a dashed line. If the inequality is not strict ( ≤ or ≥ ), graph a solid line.

Finally, pick one point that is not on either line ( (0,0) is usually the easiest) and decide whether these coordinates satisfy the inequality or not. If they do, shade the half-plane containing that point. If they don't, shade the other half-plane.

Graph each of the inequalities in the system in a similar way. The solution of the system of inequalities is the intersection region of all the solutions in the system.

Example 1:

Solve the system of inequalities by graphing:

y≤x−2y>−3x+5

First, graph the inequality y≤x−2 . The related equation is y=x−2 .

Since the inequality is ≤ , not a strict one, the border line is solid.

Graph the straight line.

Consider a point that is not on the line - say, (0,0) - and substitute in the inequality y≤x−2 .

0≤0−20≤−2

This is false. So, the solution does not contain the point (0,0) . Shade the lower half of the line.

Similarly, draw a dashed line for the related equation of the second inequality y>−3x+5 which has a strict inequality. The point (0,0) does not satisfy the inequality, so shade the half that does not contain the point (0,0) .

The solution of the system of inequalities is the intersection region of the solutions of the two inequalities.