Let f(x) = ax + b where a and b are integers. If f(f(x)) = 16x − 15, what is a possible value for a + b?
Let f(x) = ax + b where a and b are integers. If f(f(x)) = 16x − 15, what is a possible value for a + b?
- A. 1
- B. −7
- C. 9
- D. Both 1 and 9
Answer: A) 1
Explanation: f(f(x)) = a(ax+b)+b = a²x + ab + b. Equating coefficients: a² = 16 → a = 4 or −4. If a = 4, 4b+b = −15 → 5b = −15 → b = −3. Sum = 1. If a = −4, −4b+b = −15 → −3b = −15 → b = 5. Sum = 1.
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