Expert: Bobby Soltani - 8/1/2005

Question
I really need to know how to solve a system of inequalities by graphing..such as...
x+y>4
-3x+y<-1

What happends when there is a line underneath the < or > sign on a different problem..Where do I shade? Thank you so so much!

Answer
Hi Rose,

For the first problem, you first solve for y.

y > -x + 4

Now, draw the line y = -x+4.  That is a line that has a y-intercept at y = 4, and a slope of -1.  Now, since y is greater than this line, then all the area above and to the right of this line should be shaded.  The line should also be dashed(e.g. - - - - -), because y is "greater than" -x +4, not "greater than or equal to" -x + 4.  If there was a line underneath, that means "or equal to" and the line would be a solid one.

Let me know if you have any questions.

Bobby