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Math: Functions Flashcards

7 cards from real ACT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. If f(x) = 2x^2 and g(x) = x + 4, what is (f times g)(1)?

    Answer: 10

    f(1) = 2 and g(1) = 5, so the product is 10.

  2. What is the average rate of change of f(x) = x^2 from x = 1 to x = 3?

    Answer: 4

    (f(3) - f(1))/(3 - 1) = (9 - 1)/2 = 4.

  3. If f(x) = sqrt(x), what is the domain?

    Answer: x >= 0

    The square root requires a non-negative input.

  4. If f(x) = 3x + 2, by how much does f increase when x increases by 4?

    Answer: 12

    The slope is 3, so a change of 4 in x gives 3(4) = 12.

  5. Which transformation turns f(x) = x^2 into f(x) = -x^2?

    Answer: Reflection over the x-axis

    Multiplying the output by -1 reflects the graph over the x-axis.

  6. If f(x) = x^2 - 1, for what values is f(x) negative?

    Answer: -1 < x < 1

    x^2 - 1 < 0 when x^2 < 1, i.e., between -1 and 1.

  7. If f(x) = 10 - 2x, what is the x-intercept?

    Answer: 5

    Setting 10 - 2x = 0 gives x = 5.