AlgebraMediumVertex of a triangle formed by two lines and the y-axis
Algebra practice question
In the xy-plane, the lines y = 3x − 2 and y = −2x + 8 and the y-axis form a triangle. What is the x-coordinate of the vertex of the triangle that is not on the y-axis?
Answer: 2
The vertex off the y-axis is where the two lines meet: 3x − 2 = −2x + 8 → 5x = 10 → x = 2.
Common wrong answers
- If you answered 4
- 4 is the y-coordinate of that vertex (3·2 − 2).
- If you answered 8
- 8 is the y-intercept of the second line.
- If you answered -2
- −2 is the y-intercept of the first line, a vertex on the y-axis.
More Algebra questions
- Medium
A system: 2x + y = 11 and x − y = 1. What is the value of x + y? - Medium
Which of the following describes all solutions to 4x − 9 ≤ 2x + 5? - Medium
A phone's battery percentage is modeled by P = 100 − 8t, where t is the number of hours since it was unplugged… - Medium
If y = 2x − 1 and 3x + y = 14, what is the value of x? - Medium
If |2x − 3| = 7, what is the sum of all possible values of x? - Medium
Line k has equation y = (2/3)x + 1. Which equation represents a line perpendicular to line k?
Not affiliated with the College Board. SAT is a trademark of the College Board.