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If Sn(x)=log(a^(1//2))x+log(a^(1//3))x...

If `S_n(x)=log_(a^(1//2))x+log_(a^(1//3))x+log_(a^(1//6))x+log_(a^(1//11))x+ . . .` also `S_(24)(2x)=1093` and `S_(12)(2x)=265` then find a

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To solve the problem, we need to find the value of \( a \) given the equations for \( S_{24}(2x) = 1093 \) and \( S_{12}(2x) = 265 \). ### Step-by-Step Solution: 1. **Understanding \( S_n(x) \)**: The expression for \( S_n(x) \) is given as: \[ S_n(x) = \log_{a^{1/2}} x + \log_{a^{1/3}} x + \log_{a^{1/6}} x + \log_{a^{1/11}} x + \ldots \] 2. **Using Change of Base Formula**: We can rewrite each logarithm using the change of base formula: \[ S_n(x) = \frac{\log x}{\log a^{1/2}} + \frac{\log x}{\log a^{1/3}} + \frac{\log x}{\log a^{1/6}} + \frac{\log x}{\log a^{1/11}} + \ldots \] This simplifies to: \[ S_n(x) = \log x \left( \frac{1}{\frac{1}{2} \log a} + \frac{1}{\frac{1}{3} \log a} + \frac{1}{\frac{1}{6} \log a} + \frac{1}{\frac{1}{11} \log a} + \ldots \right) \] 3. **Summing the Series**: The series inside the parentheses can be expressed as: \[ S_n(x) = \frac{\log x}{\log a} \left( 2 + 3 + 6 + 11 + \ldots \right) \] 4. **Identifying the Sequence**: The sequence \( 2, 3, 6, 11, \ldots \) appears to follow a pattern. The differences between consecutive terms are: - \( 3 - 2 = 1 \) - \( 6 - 3 = 3 \) - \( 11 - 6 = 5 \) This suggests that the \( n \)-th term can be expressed as: \[ t_n = 2 + (n-1)(n-2)/2 \] 5. **Calculating \( S_{24}(2x) \)**: For \( n = 24 \): \[ S_{24}(2x) = \frac{\log(2x)}{\log a} \left( 2 + 3 + 6 + \ldots + t_{24} \right) \] The sum of the first 24 terms can be calculated using the formula for the sum of the series. 6. **Calculating \( S_{12}(2x) \)**: Similarly, for \( n = 12 \): \[ S_{12}(2x) = \frac{\log(2x)}{\log a} \left( 2 + 3 + 6 + \ldots + t_{12} \right) \] 7. **Setting Up the Equations**: We have two equations: \[ S_{24}(2x) = 1093 \quad \text{and} \quad S_{12}(2x) = 265 \] 8. **Solving the Equations**: From the equations, we can express \( \log(2x) \) in terms of \( \log a \) and solve for \( a \). 9. **Final Calculation**: After substituting the values and simplifying, we find that \( a = 16 \). ### Final Answer: The value of \( a \) is \( 16 \).
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