Question 62·Medium·Linear Inequalities in One or Two Variables
Which of the following ordered pairs satisfies the system of inequalities above?
For systems of inequalities on the SAT with only a few answer choices, the quickest method is usually to plug in each choice: substitute the given and into each inequality and see if both are true. Start with the inequality that looks easier to evaluate to eliminate as many options as possible, paying close attention to whether the inequality is strict ( or ) or inclusive ( or ).
Hints
Think about what “satisfies a system” means
A point satisfies a system of inequalities only if it makes each inequality true. If even one inequality is false, that point does not work.
Use substitution instead of graphing
For each answer choice, substitute the and values into and check if it is true. Eliminate any choices that fail this first inequality.
Check the second inequality for any remaining choices
After the first inequality, you may be left with one or more candidates. For those, plug into and see which ones still work.
Desmos Guide
Graph both inequalities
In Desmos, type y > -4x + 9 to represent (solve for first) and then type y <= 2x - 3 to represent . You should see a shaded region where the two inequalities overlap.
Check each answer choice as a point
For each answer choice, type it into Desmos as a point, like (1,4), (2,1), (0,-4), and (3,-2). See which point lies in the overlapping shaded region of both inequalities; that point is the one that satisfies the system.
Step-by-step Explanation
Understand what it means to satisfy a system of inequalities
The system is:
An ordered pair satisfies this system only if both inequalities are true when you plug in that and .
So for each answer choice:
- First check .
- Then check .
If either one is false, that choice does not work.
Test each answer choice in the first inequality
Use .
- Choice A:
, and is false. - Choice B:
, and is false (it is equal, not greater). - Choice C:
, and is false. - Choice D:
, and is true.
So far, only choice D makes the first inequality true; the others already fail the system.
Test the remaining choice in the second inequality
Now check for the remaining candidate from step 2.
- For :
Compute :
Compare to this value:
This is true, so satisfies both inequalities.
Therefore, the ordered pair that satisfies the system is .