AlgebraVery hardx-intercept of a perpendicular line through a point
Algebra practice question
In the xy-plane, lines p and q are perpendicular and intersect at (2, 3). Line p has slope 2. At what value of x does line q cross the x-axis?
Answer: 8
Line q has slope −1/2: y = 3 − (1/2)(x − 2), which is 0 when x = 8.
Common wrong answers
- If you answered -4
- −4 uses slope 1/2.
- If you answered 0.5
- 0.5 uses slope 2 for line q and solves 3 + 2(x − 2) = 0.
- If you answered 3.5
- 3.5 uses slope −2.
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