Linear Relationships Checkpoint
A free Algebra I lesson from the “Functions, Linear Relationships, and Rate of Change” unit, with a worked example and practice problems including step-by-step solutions.
This checkpoint mixes function notation, slope, graphing, and line forms. Expect to move between tables, equations, points, intercepts, and parallel or perpendicular relationships.
What you'll learn
- Evaluate functions and interpret rates of change
- Write and graph linear equations
- Compare standard, slope-intercept, and point-slope forms
Worked example
Problem. Write the line through (2, 5) with slope 3 in slope-intercept form.
- Start with point-slope form: y - 5 = 3(x - 2).
- Distribute: y - 5 = 3x - 6.
- Add 5 to get y = 3x - 1.
Answer: y = 3x - 1
Practice problems
1. If f(x) = 2x - 5, find f(8).
Show solution
- Functions: First identify exactly what the question is asking: If f(x) = 2x - 5, find f(8).
- For function notation, treat the value inside parentheses as the input and carefully substitute it into the rule.
- Substitute 8 for x.
- 2(8) - 5 = 11.
- Check the result by substituting or estimating: the response should match 11 and make sense in the original problem.
Answer: 11
2. Which relation is not a function?
Choices: (2, 1), (2, 5), (3, 6) · (1, 4), (2, 4), (3, 4) · (0, 0), (1, 2), (2, 4) · (-1, 3), (0, 3), (1, 3)
Show solution
- Functions: First identify exactly what the question is asking: Which relation is not a function?
- For function notation, treat the value inside parentheses as the input and carefully substitute it into the rule.
- The input 2 has two different outputs.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: (2, 1), (2, 5), (3, 6)
3. Find the slope through (1, 4) and (5, 12).
Show solution
- Slope: First identify exactly what the question is asking: Find the slope through (1, 4) and (5, 12).
- For slope or rate of change, compare vertical change to horizontal change and keep the sign attached to the direction of the change.
- Change in y is 8.
- Change in x is 4.
- 8/4 = 2.
- Check the result by substituting or estimating: the response should match 2 and make sense in the original problem.
Answer: 2
4. A line has slope -3 and x changes from 2 to 6. What is the change in y?
Show solution
- Slope: First identify exactly what the question is asking: A line has slope -3 and x changes from 2 to 6. What is the change in y?
- For slope or rate of change, compare vertical change to horizontal change and keep the sign attached to the direction of the change.
- The change in x is 4.
- -3 x 4 = -12.
- Check the result by substituting or estimating: the response should match -12 and make sense in the original problem.
Answer: -12
5. In y = -4x + 9, what is the y-intercept?
Show solution
- Slope-Intercept: First identify exactly what the question is asking: In y = -4x + 9, what is the y-intercept?
- For slope or rate of change, compare vertical change to horizontal change and keep the sign attached to the direction of the change.
- The y-intercept is b.
- Here b = 9.
- Check the result by substituting or estimating: the response should match 9 and make sense in the original problem.
Answer: 9
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