Algebra practice question

Answer: -3 or −3

Parallel lines have equal slopes. The second line's slope is 6/9 = 2/3. The first line's slope is −2/k, so −2/k = 2/3 gives k = −3.

Common wrong answers

If you answered 3

3 has the wrong sign; the slope of 2x + ky = 7 is −2/k, not 2/k.

If you answered 6

6 comes from matching the x-coefficients instead of the slopes.

If you answered -9

−9 copies the second line's coefficient without scaling.

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