Question one-of

1.4 Systems of Two Linear Equations - No-solution and infinite-solution cases
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One of the two equations in a linear system is 2 x plus 6 y, equals 10. The system has no solution. Which of the following could be the other equation in the system?

A.

x plus 3 y, equals 5

B.

x plus 3 y, equals negative 20

C.

6 x minus 2 y, equals 0

D.

6 x plus 2 y, equals 10

One of the two equations in a linear system is . The system has no solution.

Hard-difficulty · SAT Math · Systems of Two Linear Equations — No-solution and infinite-solution cases. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice B is correct. A system of two linear equations written in standard form has no solution when the equations are distinct and the ratio of the x-coefficient to the y-coefficient for one equation is equivalent to the ratio of the x-coefficient to the y-coefficient for the other equation. This ratio for the given equation is 2 to 6, or 1 to 3. Only choice B is an equation that isn’t equivalent to the given equation and whose ratio of the x-coefficient to the y-coefficient is 1 to 3.

Choice A is incorrect. Multiplying each of the terms in this equation by 2 yields an equation that is equivalent to the given equation. This system would have infinitely many solutions. Choices C and D are incorrect. The ratio of the x-coefficient to the y-coefficient in 6 x minus 2 y, equals 0 (choice C) is negative 6 to 2, or negative 3 to 1. This ratio in 6 x plus 2 y, equals 10 (choice D) is 6 to 2, or 3 to 1. Since neither of these ratios is equivalent to that for the given equation, these systems would have exactly one solution.