AlgebraEasy–MediumSum of the coordinates of an intersection
Algebra practice question
What is the sum of the coordinates of the point where the lines y = x + 1 and y = 3 − x cross in the xy-plane?
Answer: 3
Set x + 1 = 3 − x: 2x = 2, so x = 1, and y = 1 + 1 = 2. The point is (1, 2), and 1 + 2 = 3.
Common wrong answers
- If you answered 1
- 1 is the x-coordinate alone.
- If you answered 2
- 2 is the y-coordinate alone.
- If you answered 4
- 4 comes from the point (2, 2) or (1, 3), neither of which lies on both lines.
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