AlgebraMediumy-intercept from two points
Algebra practice question
In the xy-plane, a line passes through (1, 3) and (4, 9). What is the y-coordinate of the point where the line crosses the y-axis?
Answer: 1
Slope (9 − 3)/(4 − 1) = 2. Then 3 = 2(1) + b gives b = 1.
Common wrong answers
- If you answered 2
- 2 is the slope.
- If you answered 3
- 3 is the y-coordinate of the first point, not the intercept.
- If you answered -1
- −1 comes from b = 2 − 3, subtracting in the wrong order; b = 3 − 2(1) = 1.
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?
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