AlgebraEasy–MediumMissing coordinate of a point on a line
Algebra practice question
The point (3, k) lies on the line 2x + 3y = 3 in the xy-plane. What is the value of k?
Answer: -1 or −1
Substitute x = 3, y = k: 6 + 3k = 3, so 3k = −3 and k = −1.
Common wrong answers
- If you answered 1
- 1 has the wrong sign: 3k = 3 − 6 = −3.
- If you answered 3
- 3 comes from 3k = 9 (adding 6 instead of subtracting it).
- If you answered -3
- −3 is 3k, one step short; divide by 3.
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