SAT Math · Topic 1.2

Linear Functions Practice

Part of Algebra.

Practice questions

219

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Sample questions

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  1. Sample 1difficulty 2/5

    The graph of f(x)=3x1f(x) = 3x - 1 is reflected across the xx-axis. What is the new function?

    • A

      g(x)=3x1g(x) = -3x - 1

    • B

      g(x)=3x+1g(x) = 3x + 1

    • C

      g(x)=(3x1)2g(x) = -(3x - 1)^2

    • D

      g(x)=3x+1g(x) = -3x + 1

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    Why

    Reflection across xx-axis negates the output: g(x)=(3x1)=3x+1g(x) = -(3x-1) = -3x + 1.

  2. Sample 2difficulty 2/5

    A phone plan: \25monthlyplusmonthly plus$0.05perminute.Costforper minute. Cost form$ minutes is:

    • A

      C=25m+0.05C = 25m + 0.05

    • B

      C=0.05(m+25)C = 0.05(m + 25)

    • C

      C=25.05mC = 25.05m

    • D

      C=0.05m+25C = 0.05m + 25

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    Why

    Per-minute rate 0.050.05 is slope; monthly fee 2525 is intercept.

  3. Sample 3difficulty 2/5

    For the linear function f(x)=4x9f(x) = 4x - 9, what is the average rate of change of ff from x=2x=2 to x=7x=7?

    • A

      9

    • B

      4

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    • C

      5

    • D

      3

    Why

    For any linear function, the average rate of change equals its slope: 44.

  4. Sample 4difficulty 2/5

    A gym charges a 50membershipfeeplus50 membership fee plus20 per month. Which equation gives the total cost CC after mm months?

    • A

      C=20m+50C = 20m + 50

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    • B

      C=50m+20C = 50m + 20

    • C

      C=70mC = 70m

    • D

      C=50+20C = 50 + 20

    Why

    Monthly rate 2020 is the slope; one-time fee 5050 is the y-intercept. C=20m+50C = 20m + 50.

  5. Sample 5difficulty 2/5

    A taxi fare is F=2.50d+3F = 2.50d + 3 where dd is miles. What is the meaning of 33?

    • A

      Total fare

    • B

      Number of miles

    • C

      Cost per mile

    • D

      Initial flat fee

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    Why

    The y-intercept 33 is the fare when d=0d = 0 — the starting flat fee.