AlgebraVery hardConstant from a slope between two parametrised points
Algebra practice question
In the xy-plane, the line through the points (k, 3) and (2k, 9) has slope 2, where k is a positive constant. What is the value of k?
Answer: 3
The slope is (9 − 3)/(2k − k) = 6/k, and 6/k = 2 gives k = 3.
Common wrong answers
- If you answered 6
- 6 is the rise, not k.
- If you answered 12
- 12 multiplies 6 by 2.
- If you answered 1.5
- 1.5 divides 3 by 2.
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