AlgebraVery hardx-intercept from a slope and a point, expressed through intercept parameters
Algebra practice question
In the xy-plane, a line with slope −2 passes through the point (1, 4) and crosses the x-axis at (p, 0) and the y-axis at (0, q). What is the value of p?
Answer: 3
y = −2x + q, and 4 = −2 + q gives q = 6. Then 0 = −2p + 6, so p = 3.
Common wrong answers
- If you answered 2
- 2 comes from p = q/3, a slip in dividing.
- If you answered 6
- 6 is q, the y-intercept.
- If you answered -3
- −3 has the wrong sign.
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