AlgebraMediumy-coordinate where a line meets a vertical line
Algebra practice question
In the xy-plane, the graph of 9x − 4y = 6 intersects the vertical line x = 2 at exactly one point. What is the y-coordinate of that point?
Answer: 3
On the line x = 2, substitute x = 2 into 9x − 4y = 6: 18 − 4y = 6, so 4y = 12 and y = 3.
Common wrong answers
- If you answered 6
- 6 comes from solving 18 − 4y = 6 as 4y = 24.
- If you answered -3
- −3 has the wrong sign; 18 − 4y = 6 gives 4y = 12, not −12.
- If you answered -1.5
- −1.5 is the y-intercept (where x = 0), not the value at x = 2.
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