Answers:
Refer to the graph below
Two solution points are (-5,-4) and (-4,-3)
Non solution points are (0,3) and (1,4)
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Explanation:
The boundary line for [tex]y \ge 3x+3[/tex] is [tex]y = 3x+3[/tex]
This linear equation has a y intercept of (0,3) and another point on the line is (1,6). Plot these two points and draw a straight line through them. This line is a solid boundary line because of the "or equal to" as part of the inequality sign. This means points on the boundary adjacent to the shaded region area part of the solution set.
Because of the "greater than" portion, we'll shade above the solid boundary line. This only works because y is isolated.
Keep in mind that we're also told that [tex]y < -2[/tex] which means we'll also shade the region below the boundary line [tex]y = -2[/tex]. This is a dashed line through -2 on the y axis. A dashed line does not include points on the boundary as part of the solution.
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To summarize: We shade above y = 3x+3 (solid) but below y = -2 (dashed).
Refer to the diagram below to see what's going on.
The entire southwest region is shaded.
That blue shaded region represents all (x,y) points that make the system true.
For example, the point (-5,-4) is in the blue region.
Notice how plugging the coordinates into the first inequality gets us...
[tex]y \ge 3x+3\\\\-4 \ge 3(-5)+3\\\\-4 \ge -15+3\\\\-4 \ge -12\\\\[/tex]
which is a true statement. If you plugged y = -4 into [tex]y < -2[/tex], you would also get another true statement.
Both inequalities are true for (x,y) = (-5,-4) which confirms it to be a solution point.
You should also find that a point like (-4,-3) is another solution in the blue region following similar steps. There are infinitely many solution points to pick from. Feel free to choose others.
Non-solution points are such that they aren't in the shaded region. We could also pick points on the dashed boundary line as non-solutions.
Side note: you can pick points on the solid boundary as solution points, but those points must be adjacent to the shaded region. The point (0,3) is NOT a solution even though it's on the solid boundary line.
