Subscribe

9th grade · Math · Unit 10 of 17

Function Notation

f(x), domain and range

What your child practices

Evaluating and solving with function notation, and naming the domain and range of a function, including a sensible domain in a real situation.

Arizona Academic Standards learning standard: A1.F-IF.A.1; A1.F-IF.A.2; A1.F-IF.B.5 · functions as rules, function notation, and the domain of a function in context

How we explain it

Children can open this short lesson before they practice.

  1. f(x) is the output of f when the input is x.
  2. To find f(3), replace every x with 3.
  3. The domain is all the inputs. The range is all the outputs.

Example: f(x) = 2x − 5. What is f(4)? 2 × 4 − 5 = 8 − 5. Answer: 3

Function Notation in Arizona

In the Arizona Academic Standards, this is unit 10 of 17 in 9th grade Math, after Data & Scatter Plots and before Linear Inequalities.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Arizona Department of Education

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    f(x) = −4x − 9. For which x is f(x) = 15?

    • -6
    • 6
    • 15
    • -5

  2. Question 2

    If f(x) = 5x + 1, what is f(1)?

    answer box

  3. Question 3

    What is the domain of {(−3, 1), (−1, 2), (1, 0), (2, 8)}?

    • {−3, −1, 0, 1, 2, 8}
    • {0, 1, 2, 8}
    • {−2, 0, 2, 3}
    • {−3, −1, 1, 2}

  4. Question 4

    P(w) = 15w gives pay for w whole weeks worked in a 10-week summer job. Which domain makes sense?

    • Whole numbers from 0 to 10
    • Negative whole numbers
    • All real numbers
    • Any number from 0 to 150

  5. Question 5

    If f(x) = −x + 5, what is f(−1)?

    answer box

  6. Question 6

    What is the range of {(−1, 6), (1, 6), (4, 1), (5, 9)}?

    • {2, 7, 10}
    • {1, 6, 9}
    • {−1, 1, 4, 5}
    • {−1, 1, 4, 5, 6, 9}

More 9th grade