8th Grade Math Practice Test: Functions
Name: _____________________________ Date: _________________
Instructions: Answer the following questions to the best of your ability. You may use a
calculator where necessary. Show all work for full credit.
1. What is a function? Explain in your own words and provide an example.
2. Consider the function f(x) = 3x + 4. What is the value of f(2)?
3. Write a function that models the relationship between the number of weeks (w) and the
number of hours (h) you spend practicing a musical instrument if you practice 5 hours each
week.
4. Graph the function g(x) = x^2 - 4x + 3. Label the x-axis, y-axis, and the vertex of the
parabola.
5. Compare the functions f(x) = 2x and g(x) = x^2. At what value of x do both functions have
the same value?
6. Given the function h(x) = 4x - 7, find the value of x when h(x) = 9.
7. The temperature (T), in degrees Celsius, as a function of the number of hours (h) after 6
a.m. is given by T(h) = -0.5h^2 + 4h + 10. What is the temperature at 10 a.m.?
8. Create a table of values for the function f(x) = -2x + 5 for x = -1, 0, 1, 2, 3.
9. How does changing the coefficient of x in a linear function f(x) = mx + b affect its graph?
Explain.
