2002 AMC 12A Problem 19

Attempt Problem 19 of the 2002 AMC 12A below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2002 AMC 12A solutions, or check the answer key.

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19.

The graph of the function ff is shown below. How many solutions does the equation f(f(x))=6f(f(x)) = 6 have?

22

44

55

66

77

Answer: D
Concepts:functiondata and graph interpretation
Difficulty rating: 1660
Solution:

The graph reaches 66 at x=2x = -2 and x=1,x = 1, so f(f(x))=6f(f(x)) = 6 requires f(x)=2f(x) = -2 or f(x)=1.f(x) = 1.

The horizontal line y=2y = -2 meets the graph twice, and y=1y = 1 meets it four times, giving 2+4=62 + 4 = 6 solutions.

Thus, the correct answer is D.

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