Question 89·Medium·Linear Inequalities in One or Two Variables
Which of the following ordered pairs satisfies the system of inequalities above?
For systems of inequalities with answer choices given as points, the fastest SAT strategy is usually to test the choices directly: for each , substitute the into each expression on the right, compare with using the correct inequality sign (remembering that and do not allow equality but and do), and eliminate any choice that fails even one inequality. Work systematically through the options until you find the one point that satisfies all inequalities.
Hints
Think about what a solution to a system means
A point is a solution to a system of inequalities only if it makes every inequality in the system true, not just one of them.
Use substitution for each answer choice
Pick an answer choice and plug its -value into each right-hand side ( and ), then compare the result with the given -value using the inequality sign.
Pay attention to strict vs. non-strict inequalities
Remember that does not allow equality, while does. A point exactly on the line for will not satisfy .
Eliminate choices systematically
Check each ordered pair against both inequalities. As soon as one inequality fails, you can eliminate that choice and move on.
Desmos Guide
Graph the inequalities
In Desmos, enter the two inequalities on separate lines: y > -2x + 4 and y <= x - 1. Desmos will shade the region that satisfies each inequality; the solution set is where the shadings overlap.
Plot each answer choice as a point
Enter each option as a point on separate lines, for example (2,0), (1,0), (3,1), (2,2). Visually check for each point whether it lies inside the overlapping shaded region that represents solutions to both inequalities (and not just on a boundary excluded by >). The point that lies in this overlapping region is the solution.
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, when you plug in its and values, both inequalities are true at the same time. If even one inequality is false, that ordered pair is not a solution.
Check how to test a point in each inequality
Take a generic point .
- In the first inequality , substitute the -value into , compute the result, and compare it with the -value. The -value must be greater than that result.
- In the second inequality , substitute the same -value into , compute it, and check that the -value is less than or equal to that result.
We will apply this procedure to the answer choices one by one.
Test choices that do not work
Choice A:
- First inequality: becomes . This says , which is false because does not allow equality. So does not satisfy the system.
Choice B:
- First inequality: becomes . This says , which is clearly false. So does not satisfy the system.
Choice D:
- First inequality: becomes . This says , which is true.
- Second inequality: becomes . This says , which is false. So does not satisfy the system either.
Only one choice remains to test.
Test the remaining choice and identify the solution
Choice C:
- First inequality: becomes . This is , which is true.
- Second inequality: becomes . This is , which is also true.
Since makes both inequalities true, it is the ordered pair that satisfies the system.
Answer: .