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Let \(f(x)=2^x\). Which rule is obtained from \(f\) by a horizontal compression by a factor of \(\frac{1}{3}\)? Briefly explain what the coefficient \(3\) is multiplying in the correct rule.
A. \(g(x)=2^{3x}\)
B. \(g(x)=3\cdot2^x\)
C. \(g(x)=2^{x+3}\)
Hints
- Decide whether each visible \(3\) acts on the input or on the output.
- A horizontal change is made inside the function's input.
- Compare each option with the form \(f(cx)\).
Solution
1. A horizontal compression by a factor of \(\frac{1}{3}\) is produced by replacing the input \(x\) with \(3x\).
2. Therefore, \(g(x)=f(3x)=2^{3x}\).
3. In this rule, the coefficient \(3\) multiplies the input \(x\), not the output of the exponential function.
Answer
A. \(g(x)=2^{3x}\). The coefficient \(3\) multiplies the input \(x\).
