how do I do -5x -2y less than or equal to -8 on the graph

Question

In steps how do I do -5x-2y less than or equal to -8 on the graph?  I dont understand how to graph inequalities

Answer 1

Hi Toni-

i'm from Michigan originally :).  Anyway, here is how you graph an inequality:

 

1.  Put the function into slope-intercept form:

-5x - 2y <= -8

-2y <= 5x - 8

y >= -(5/2)x + 4 (you flip the inequality symbol when you divide both sides by a negative)

 

2.  Look at whether the inequality is less than or greater than; if it is, then you use a dotted line.  But, if it is either less than or equal to or greater than or equal to, you use a solid line.

 

3.  Graph the function as if it were a typical function (in this case, graph y = (-5/2)x + 4

 

4.  Then shade either below or above the line.  Since this is y>= (-5/2)x + 4, you shade above the function line.  If it were less than, you would shade below.

 

 

Answer 2

To add on to that.  If you are having difficulties determining which side of the function to shade (as a lot of students do), you can also test a point such as (0,0) and if it makes the function true, then that side of the function is shaded.