How functions practice works
Each page in this series holds one topic from the ACT Math test. The list on the left shows every question in the pool; the number tile turns green once you have checked a question, and a saved question is easy to find again with the Bookmarked filter.
- Pick a question. Use the list, the search box or the difficulty filter, or just press Next question to go in order.
- Answer it. One problem at a time with four answer choices. Some official ACT Math questions share a graph or chart; calculators are permitted only on Math.
- Check your answer. Your result shows every choice marked, your pick, the correct option and a short explanation of why.
- Try it again or move on. A question you got wrong is worth a second attempt after you have read the explanation.
Prefer a short set with a score at the end? Build a functions set of 5, 10 or 20 questions, timed or untimed.
What functions covers on the ACT
On the ACT Math test, Functions questions map to Preparing for Higher Math. Our practice results show raw accuracy for this category so you can identify a skill to revisit. Official ACT reports use their own scoring method.
How to approach functions
Read f(x) as the output for a specific input. When the question shows a graph or table, locate the input first; for composition, evaluate the inner function before the outer one.
Before you move on: Confirm whether the question asks for an input, an output, a rate of change or a feature of the graph.
The 50 questions here cover 49 skills, including:
- Evaluating a linear function
- Evaluating a quadratic function at a negative input
- Reading function values from a table
- Slope of a linear function
- Linear cost function in context
- Domain of a square root function
- Equation of a linear function from its graph
- Evaluating an exponential function
- Vertical translation
- Evaluating a piecewise function
- Zero of a linear function
- Evaluating a composition
This pool has 16 questions labelled easy, 18 medium and 16 hard by our team. These are practice labels, not official ACT difficulty ratings. Filter when you want to warm up or stretch. All 50 questions are available to practice.
Tips for functions questions
- Write down what the question asks for before you calculate. Many wrong answers are correct values for a different quantity.
- Estimate first. If the choices are far apart, a quick estimate rules out two or three of them.
- Plug the answer choices back in when the algebra gets long; the ACT rewards whatever method is fastest and correct.
- Check units and signs at the end. A negative that should be positive is easy to overlook.