To analyze the transformation from \( f(x) = x \) to \( f(3x) - 13 = 3x - 13 \), we can break it down into steps:
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Start with the function:
- \( f(x) = x \)
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Apply the transformation \( f(3x) \):
- This transformation involves substituting \( 3x \) in place of \( x \).
- The function now becomes \( f(3x) = 3x \).
- This represents a horizontal compression by a factor of 3 (because we are multiplying \( x \) by 3).
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Then apply \( f(3x) - 13 \):
- Now we subtract 13 from the result: \( 3x - 13 \).
- This corresponds to a vertical shift downward of 13 units.
Conclusion: The overall transformation from \( f(x) = x \) to \( f(3x) - 13 = 3x - 13 \) consists of a horizontal compression by a factor of 3 and a vertical shift downward by 13 units.
The correct answer is: compressed horizontally and shifted down.