To find a quartic function with only real zeros at x = 9 and x = -1, we can construct the function based on the given roots. The function must include these zeros in such a way that the total degree is 4 and there are no additional real zeros.
Analysis of Options:
A. :
- Real Zeros: The zeros from (x - 9), (x + 1), and are x = 9, x = -1, and x = 1.
- Total Zeros: This function has three real zeros instead of only two required zeros.
- Conclusion: This function does not meet the requirement.
B. :
- Real Zeros: The zeros from (x - 9) and (x + 1) are x = 9 and x = -1. The factor () has complex zeros x = i and x = -i.
- Conclusion: This function has only the real zeros x = 9 and x = -1, so it meets the requirement.
C.