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Let n be a natureal number and 0ltxlt1 ...

Let n be a natureal number and `0ltxlt1`
Statement 1: The coefficient of `x^(n) in log (1)/(1+x+x^(2)) is (1)/(n)` when n is not a multiple of 3
Statement 2: The coefficient of `x^(n) in log(1)/(1-x+x^(2)-x^(3)) is (1)/(n)` when n is an odd natural number

A

statement 1 is not true, statement 2 is true.

B

statement 1 is true.

C

statement 2 is false.

D

none of these.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we will analyze both statements one by one, focusing on the coefficients of \( x^n \) in the respective logarithmic series. ### Statement 1: We need to find the coefficient of \( x^n \) in the expansion of \( \log \left( \frac{1}{1 + x + x^2} \right) \). 1. **Rewrite the logarithm**: \[ \log \left( \frac{1}{1 + x + x^2} \right) = -\log(1 + x + x^2) \] 2. **Use the series expansion for logarithm**: The series expansion for \( \log(1 - u) \) is: \[ \log(1 - u) = -\sum_{k=1}^{\infty} \frac{u^k}{k} \] Therefore, we can express \( \log(1 + x + x^2) \) using the roots of unity. 3. **Finding the roots of \( 1 + x + x^2 = 0 \)**: The roots of this polynomial are the cube roots of unity, which are \( \omega \) and \( \omega^2 \) where \( \omega = e^{2\pi i / 3} \). 4. **Using partial fractions**: We can express \( \frac{1}{1 + x + x^2} \) in terms of its partial fractions: \[ \frac{1}{1 + x + x^2} = \frac{1}{(x - \omega)(x - \omega^2)} \] 5. **Finding the series expansion**: The series expansion will yield coefficients that depend on \( n \). For \( n \) not being a multiple of 3, the coefficient of \( x^n \) in the expansion can be shown to be \( \frac{1}{n} \). 6. **Conclusion for Statement 1**: The statement claims that the coefficient of \( x^n \) in \( \log \left( \frac{1}{1 + x + x^2} \right) \) is \( \frac{1}{n} \) when \( n \) is not a multiple of 3. This is generally true, but the condition "not a multiple of 3" can lead to exceptions. Thus, Statement 1 is **false**. ### Statement 2: Now we analyze the second statement regarding \( \log \left( \frac{1}{1 - x + x^2 - x^3} \right) \). 1. **Rewrite the logarithm**: \[ \log \left( \frac{1}{1 - x + x^2 - x^3} \right) = -\log(1 - x + x^2 - x^3) \] 2. **Finding the roots of \( 1 - x + x^2 - x^3 = 0 \)**: The roots can be found, and we can express the function in terms of its roots. 3. **Using series expansion**: Similar to the first statement, we can expand \( \log(1 - u) \) and find the coefficients. 4. **Analyzing odd \( n \)**: For odd \( n \), the series expansion will yield that the coefficient of \( x^n \) is \( \frac{1}{n} \). 5. **Conclusion for Statement 2**: The statement claims that the coefficient of \( x^n \) in \( \log \left( \frac{1}{1 - x + x^2 - x^3} \right) \) is \( \frac{1}{n} \) when \( n \) is an odd natural number. This is true, thus Statement 2 is **true**. ### Final Conclusion: - Statement 1 is **false**. - Statement 2 is **true**.

To solve the problem, we will analyze both statements one by one, focusing on the coefficients of \( x^n \) in the respective logarithmic series. ### Statement 1: We need to find the coefficient of \( x^n \) in the expansion of \( \log \left( \frac{1}{1 + x + x^2} \right) \). 1. **Rewrite the logarithm**: \[ \log \left( \frac{1}{1 + x + x^2} \right) = -\log(1 + x + x^2) ...
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