Systems of Two Linear Equations in Two Variables

SAT Math· difficulty 5/5

For what value(s) of kk does the system 2x+ky=42x + ky = 4 and 4x+6y=k4x + 6y = k have NO solution?

  • A

    k=8k = 8 only

  • B

    k=3k = 3 only

  • C

    k=3k = 3 and k8k \neq 8

    check_circle
  • D

    k=3k = -3

Explanation

Coefficient ratio: 24=k6\frac{2}{4} = \frac{k}{6}k=3k = 3. Constant ratio: 4k\frac{4}{k}. No solution requires 4k12\frac{4}{k} \neq \frac{1}{2}, i.e., k8k \neq 8. So k=3k = 3 and k8k \neq 8.

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