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9th grade · Math · Unit 7 of 19

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.

Oregon State Standards learning standard: HS.AFN.A.1; HS.AFN.A.2; HS.AFN.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

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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