SAT Math · Linear equations in one variable · medium

For what value of k does the equation 5(x-2)+12 = kx+6 have no solution?

For what value of kk does the equation 5(x−2)+12=kx+65(x-2)+12 = kx+6 have no solution?

Answer and explanation

Answer: A: 5

Distribute on the left: 5(x−2)+12=5x−10+12=5x+25(x-2)+12 = 5x - 10 + 12 = 5x + 2, so the equation is 5x+2=kx+65x + 2 = kx + 6. A linear equation has no solution when both sides have the same xx-coefficient but different constants. Setting k=5k = 5 gives 5x+2=5x+65x + 2 = 5x + 6, which simplifies to 2=62 = 6, impossible. So k=5k = 5, choice A. Choice B (k=6k=6) matches the constant term, not the coefficient, and gives one solution. Choice C (−5-5) is a sign slip and gives x=−0.4x = -0.4. Choice D (k=2k=2) mixes up the constant on the left and also gives one solution.

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