SOLUTION: Solve the following system of linear inequalities by graphing. x – 3y > 6 3x + 2y > 12

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Question 85717: Solve the following system of linear inequalities by graphing.
x – 3y > 6
3x + 2y > 12

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
16.

Start with the given system of inequalities
x-3y%3E6

3x%2B2y%3E12



In order to graph this system of inequalities, we need to graph each inequality one at a time.

So lets graph the first inequality

In order to graph x-3y%3E6 we need to graph the equation x-3y=6 (just replace the inequality sign with an equal sign). So lets graph the line x-3y=6 (note: if you need help with graphing, check out this solver)
graph%28+400%2C+300%2C+-10%2C+10%2C+-10%2C+10%2C%286-1%2Ax%29%2F-3%29 graph of x-3y=6
Now lets pick a test point, say (0,0) (any point will work, but this point is the easiest to work with), and evaluate the inequality x-3y%3E6
%280%29-3%280%29%3E6 Plug in x=0, y=0

0%3E6 Simplify


Since this inequality is not true, we shade the entire region that doesn't contain (0,0)



Here is the graph of x-3y%3E6 with the graph of the line(x-3y=6) in red and the shaded region in green
(note: The red line should be a dashed line since it is not included in the region. Since the inequalityis a > sign, it tells us not to include the boundaries.)




Now lets graph the second inequality

In order to graph 3x%2B2y%3E12 we need to graph the equation 3x%2B2y=12 (just replace the inequality sign with an equal sign). So lets graph the line 3x%2B2y=12 (note: if you need help with graphing, check out this
solver)
graph%28+400%2C+300%2C+-10%2C+10%2C+-10%2C+10%2C%2812-3%2Ax%29%2F2%29 graph of 3x%2B2y=12
Now lets pick a test point, say (0,0) (any point will work, but this point is the easiest to work with), and evaluate the inequality 3x%2B2y%3E12
3%280%29%2B2%280%29%3E12 Plug in x=0, y=0

0%3E12 Simplify


Since this inequality is not true, we shade the entire region that doesn't contain (0,0)



Here is the graph of 3x%2B2y%3E12 with the graph of the line(3x%2B2y=12) in red and the shaded region in green
(note: The red line should be a dashed line since it is not included in the region. Since the inequalityis a > sign, it tells us not to include the boundaries.)
So we essentially have these 2 regions
Region #1 which is the graph of x-3y%3E6
Region #2 which is the graph of 3x%2B2y%3E12


So these regions overlap to produce this region. It's a little hard to see, but after evenly shading each region, the intersecting region will be the most shaded in.

Here is a cleaner look at the intersection of regions

Here is the intersection of the 2 regions represented by the dots