Question which-

5.1 Linear Inequalities in One or Two Variables - Systems of inequalities and feasible region
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y is less than or equal to, 3 x plus 1
x minus y is greater than 1

Which of the following ordered pairs (x, y) satisfies the system of inequalities above?

A.

negative 2 comma negative 1​​​​​​​

B.

negative 1 comma 3​​​​​​​

C.

1 comma 5​​​​​​​

D.

2 comma negative 1​​​​​​​

Which of the following ordered pairs ( x , y ) satisfies the system of inequalities

Hard-difficulty · SAT Math · Linear Inequalities in One or Two Variables — Systems of inequalities and feasible region. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice D is correct. Any point (x, y) that is a solution to the given system of inequalities must satisfy both inequalities in the system. The second inequality in the system can be rewritten as x is greater than, y plus 1. Of the given answer choices, only choice D satisfies this inequality, because inequality 2 is greater than, negative 1 plus 1 is a true statement. The point with coordinates 2 comma negative 1 also satisfies the first inequality.

Alternate approach: Substituting the ordered pair 2 comma negative 1 into the first inequality gives negative 1 is less than or equal to, 3 times 2, plus 1, or negative 1 is less than or equal to 7, which is a true statement. Substituting the ordered pair 2 comma negative 1 into the second inequality gives 2 minus negative 1, is greater than 1, or 3 is greater than 1, which is a true statement. Therefore, since the ordered pair 2 comma negative 1 satisfies both inequalities, it is a solution to the system.

Choice A is incorrect because substituting −2 for x and −1 for y in the first inequality gives negative 1 is less than or equal to, 3 times negative 2, plus 1, or negative 1 is less than or equal to negative 5, which is false. Choice B is incorrect because substituting −1 for x and 3 for y in the first inequality gives 3 is less than or equal to, 3 times negative 1, plus 1, or 3 is less than or equal to negative 2, which is false. Choice C is incorrect because substituting 1 for x and 5 for y in the first inequality gives 5 is less than or equal to, 3 times 1, plus 1, or 5 is less than or equal to 4, which is false.