Question y-62-1

5.1 Linear Inequalities in One or Two Variables - Systems of inequalities and feasible region
0:00

y>14

4x+y<18

The point x,53 is a solution to the system of inequalities in the xy-plane. Which of the following could be the value of x ?

A.

-9

B.

-5

C.

5

D.

9

y &#62; 14 4 x + y &#60; 18 The point x , 53 is a

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 A is correct. It’s given that the point x,53 is a solution to the given system of inequalities in the xy-plane. This means that the coordinates of the point, when substituted for the variables x and y , make both of the inequalities in the system true. Substituting 53 for y in the inequality y>14 yields 53>14, which is true. Substituting 53 for y in the inequality 4x+y<18 yields 4x+53<18. Subtracting 53 from both sides of this inequality yields 4x<-35. Dividing both sides of this inequality by 4 yields x<-8.75. Therefore, x must be a value less than -8.75 . Of the given choices, only -9 is less than -8.75 .

Choice B is incorrect. Substituting -5 for x and 53 for y in the inequality 4x+y<18 yields 4-5+53<18, or 33<18, which is not true.

Choice C is incorrect. Substituting 5 for x and 53 for y in the inequality 4x+y<18 yields 45+53<18, or 73<18, which is not true.

Choice D is incorrect. Substituting 9 for x and 53 for y in the inequality 4x+y<18 yields 49+53<18, or 89<18, which is not true.