AlgebraEasy–Mediumx-coordinate where two lines meet
Algebra practice question
In the xy-plane, the lines y = 3x and y = x + 4 intersect at the point (a, b). What is the value of a?
Answer: 2
Set 3x = x + 4: 2x = 4, so x = 2.
Common wrong answers
- If you answered 4
- 4 is the y-intercept of the second line.
- If you answered 6
- 6 is b, the y-coordinate of the intersection.
- If you answered -2
- −2 comes from 3x − x = −4, a sign slip.
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