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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.

Washington State Learning Standards learning standard: M.HS.DA.FIF.1; M.HS.DA.FIF.2; M.HS.R.FIF.5 · using function notation, evaluating functions, and relating the domain and range to the situation

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

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

    What is the domain of {(−3, 7), (−1, −4), (2, 8), (5, 5)}?

    • {−3, −1, 2, 5}
    • {−2, 0, 3, 6}
    • {−4, 5, 7, 8}
    • {−4, −3, −1, 2, 5, 7, 8}

  2. Question 2

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

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

  3. Question 3

    If f(x) = −2x − 1, what is f(4)?

    answer box

  4. Question 4

    f(x) = 4x − 7. For which x is f(x) = 13?

    • -5
    • 6
    • 13
    • 5

  5. Question 5

    f(x) = −3x + 6. For which x is f(x) = −12?

    • -12
    • 6
    • -6
    • 7

  6. Question 6

    What is the range of {(−3, 3), (−1, −4), (1, −4), (5, 7)}?

    • {−4, 3, 7}
    • {−3, −1, 1, 5}
    • {−4, −3, −1, 1, 3, 5, 7}
    • {−3, 4, 8}

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