Grade 8 Functions Test PDF
Free preview of a printable Grade 8 Functions test with a complete step-by-step answer key. Common Core 8.F aligned · balanced 5/3/2 difficulty.
1. If f(x) = 2x + 3, find f(4).
2. Find the slope of the line through (0, 1) and (2, 5).
3. Identify the y-intercept of y = 3x − 7.
4. Is {(1,2),(2,4),(3,6)} a function?
5. Write the equation of a line with slope 3 and y-intercept 2.
6. If f(x) = 2x + 5, solve f(x) = 19.
7. Find the slope of 4x − 2y = 8.
8. Compare slopes of y = 2x + 1 and y = 3x − 4. Which is steeper?
9. A line passes through (1, 4) and (3, 10). Write its equation.
10. f(x) is linear. f(2) = 7, f(5) = 16. Find f(x).
1. 11
f(4) = 2(4) + 3 = 8 + 3 = 11
2. 2
(5 − 1)/(2 − 0) = 4/2 = 2
3. −7
Slope-intercept form: y = mx + b → b = −7
4. Yes
Each input has exactly one output → function.
5. y = 3x + 2
y = mx + b with m = 3, b = 2
6. x = 7
2x + 5 = 19 → 2x = 14 → x = 7
7. 2
−2y = −4x + 8 → y = 2x − 4 → m = 2
8. y = 3x − 4
|3| > |2| → steeper
9. y = 3x + 1
m = (10−4)/(3−1) = 3; y − 4 = 3(x − 1) → y = 3x + 1
10. f(x) = 3x + 1
m = (16−7)/(5−2) = 3; 7 = 3(2) + b → b = 1
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Topics covered
Function notation, slope, intercepts, linear functions, comparing functions.
Difficulty balance
5 easy / 3 medium / 2 hard — fair grading across abilities.
Answer key
Step-by-step solutions for every question.