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at a movie theater, patrons earn 1 point for every $5 they spend, plus …

Question

at a movie theater, patrons earn 1 point for every $5 they spend, plus 20 bonus points on their first movie. if function (f) represents the number of points earned as a function of the total amount spent (x), which function represents the total amount spent as a function of the number of points earned?

a. (f^{-1}(x) = 0.2x + 100)
b. (f^{-1}(x) = 0.2x - 100)
c. (f^{-1}(x) = 5x + 100)
d. (f^{-1}(x) = 5x - 100)

Explanation:

Set up the function for points earned

$$ f(x) = \frac{1}{5}x + 20 = 0.2x + 20 $$

Solve for x in terms of f(x)

$$ LATEXBLOCK0 $$

Write the inverse function

$$ f^{-1}(x) = 5x - 100 $$

Answer:

  • A. \(f^{-1}(x) = 0.2x + 100\)
  • B. \(f^{-1}(x) = 0.2x - 100\)
  • C. \(f^{-1}(x) = 5x + 100\)
  • D. \(f^{-1}(x) = 5x - 100\) (Correct answer)