Algebra practice question

Answer: 4

2x + y = 7 has slope −2, so the perpendicular has slope 1/2. Then (k − 2)/(5 − 1) = 1/2, so k = 4.

Common wrong answers

If you answered 0

0 uses slope −1/2.

If you answered 10

10 uses slope 2, forgetting the negative reciprocal's sign.

If you answered -6

−6 uses slope −2 (parallel, not perpendicular).

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