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Evaluate m=1(2m)!m2m\sum_{m=1} \frac{(2m)!}{m^{2m}}

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Q. Evaluate m=1(2m)!m2m\sum_{m=1} \frac{(2m)!}{m^{2m}}
  1. Understand Notation and Terms: We are asked to evaluate the infinite series m=1(2m)!m2m\sum_{m=1}^{\infty} \frac{(2m)!}{m^{2m}}. This is a series where each term is the factorial of twice an integer mm, divided by mm raised to the power of 2m2m.
  2. Calculate First Few Terms: The first step is to understand the notation and the terms of the series. The factorial of a number nn, denoted n!n!, is the product of all positive integers less than or equal to nn. The notation m2mm^{2m} means mm raised to the power of 2m2m.
  3. Evaluate Convergence: Let's calculate the first few terms of the series to get an idea of what the series looks like:\newlineFor m=1m=1: (21)!1(21)=2!12=21=2\frac{(2\cdot 1)!}{1^{(2\cdot 1)}} = \frac{2!}{1^2} = \frac{2}{1} = 2\newlineFor m=2m=2: (22)!2(22)=4!24=2416=1.5\frac{(2\cdot 2)!}{2^{(2\cdot 2)}} = \frac{4!}{2^4} = \frac{24}{16} = 1.5\newlineFor m=3m=3: (23)!3(23)=6!36=7207290.987\frac{(2\cdot 3)!}{3^{(2\cdot 3)}} = \frac{6!}{3^6} = \frac{720}{729} \approx 0.987
  4. Apply Ratio Test: We can see that as mm increases, the factorial grows much faster than the exponential term in the denominator. However, the factorial is divided by a rapidly increasing exponential term, which suggests that the terms of the series decrease as mm increases.
  5. Simplify Ratio Expression: To evaluate the sum, we would typically look for a pattern or a closed-form expression. However, this series does not have a simple closed-form expression, and it is not a well-known series like a geometric or arithmetic series. Therefore, we cannot find an exact sum in a simple form.
  6. Take Limit as mm Approaches Infinity: Since we cannot find a closed-form expression for the sum, we can consider whether the series converges or diverges. If it converges, we can say that there is a finite sum, even if we cannot find the exact value. To test for convergence, we can use the ratio test.
  7. Conclude Convergence: The ratio test states that for a series n=1an\sum_{n=1}^{\infty} a_n, if the limit as nn approaches infinity of an+1/an|a_{n+1}/a_n| is less than 11, the series converges. Let's apply the ratio test to our series:\newlineam=(2m)!m2ma_m = \frac{(2m)!}{m^{2m}}\newlineam+1=(2(m+1))!(m+1)2(m+1)a_{m+1} = \frac{(2(m+1))!}{(m+1)^{2(m+1)}}\newlineWe need to find the limit of am+1/am|a_{m+1}/a_m| as mm approaches infinity.
  8. Determine Sum Approximation: Calculate the ratio am+1/am|a_{m+1}/a_m|:
    am+1/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{m+1}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|
    Simplify the ratio by canceling out common terms:
    am+1/am=(2m+2)(2m+1)(2m)!((m+1)2m+2)/(2m)!(m2m)|a_{m+1}/a_m| = \left|\frac{(2m+2)(2m+1)(2m)!}{((m+1)^{2m+2})} / \frac{(2m)!}{(m^{2m})}\right|
    am+1/am=(2m+2)(2m+1)(m+1)2m2m((m+1)2m)|a_{m+1}/a_m| = \left|\frac{(2m+2)(2m+1)}{(m+1)^{2}} \cdot \frac{m^{2m}}{((m+1)^{2m})}\right|
    am+1/am=(2m+2)(2m+1)(m+1)2m+2|a_{m+1}/a_m| = \left|\frac{(2m+2)(2m+1)}{(m+1)^{2m+2}}\right|
  9. Determine Sum Approximation: Calculate the ratio a(m+1)/am|a_{(m+1)}/a_m|:
    a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|
    Simplify the ratio by canceling out common terms:
    a(m+1)/am=(2m+2)(2m+1)(2m)!((m+1)2m+2)/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2m+2)(2m+1)(2m)!}{((m+1)^{2m+2})} / \frac{(2m)!}{(m^{2m})}\right|
    a(m+1)/am=(2m+2)(2m+1)(m+1)2m2m((m+1)2m)|a_{(m+1)}/a_m| = \left|\frac{(2m+2)(2m+1)}{(m+1)^{2}} \cdot \frac{m^{2m}}{((m+1)^{2m})}\right|
    a(m+1)/am=(2m+2)(2m+1)(m+1)2m+2|a_{(m+1)}/a_m| = \left|\frac{(2m+2)(2m+1)}{(m+1)^{2m+2}}\right|Now, we simplify the expression further and take the limit as mm approaches infinity:
    a(m+1)/am=4m2+6m+2(m+1)2m+2|a_{(m+1)}/a_m| = \left|\frac{4m^2 + 6m + 2}{(m+1)^{2m+2}}\right|
    As mm approaches infinity, the highest power of mm in the numerator is m2m^2, and in the denominator, it is a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|00, which grows much faster than m2m^2. Therefore, the limit of this ratio as mm approaches infinity is a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|33.
  10. Determine Sum Approximation: Calculate the ratio a(m+1)/am|a_{(m+1)}/a_m|:
    a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|
    Simplify the ratio by canceling out common terms:
    a(m+1)/am=(2m+2)(2m+1)(2m)!((m+1)2m+2)/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2m+2)(2m+1)(2m)!}{((m+1)^{2m+2})} / \frac{(2m)!}{(m^{2m})}\right|
    a(m+1)/am=(2m+2)(2m+1)(m+1)2m2m((m+1)2m)|a_{(m+1)}/a_m| = \left|\frac{(2m+2)(2m+1)}{(m+1)^{2}} \cdot \frac{m^{2m}}{((m+1)^{2m})}\right|
    a(m+1)/am=(2m+2)(2m+1)(m+1)2m+2|a_{(m+1)}/a_m| = \left|\frac{(2m+2)(2m+1)}{(m+1)^{2m+2}}\right|Now, we simplify the expression further and take the limit as mm approaches infinity:
    a(m+1)/am=4m2+6m+2(m+1)2m+2|a_{(m+1)}/a_m| = \left|\frac{4m^2 + 6m + 2}{(m+1)^{2m+2}}\right|
    As mm approaches infinity, the highest power of mm in the numerator is m2m^2, and in the denominator, it is a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|00, which grows much faster than m2m^2. Therefore, the limit of this ratio as mm approaches infinity is a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|33.Since the limit of a(m+1)/am|a_{(m+1)}/a_m| as mm approaches infinity is a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|33, which is less than a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|77, the ratio test tells us that the series converges.
  11. Determine Sum Approximation: Calculate the ratio a(m+1)/am|a_{(m+1)}/a_m|:
    a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|
    Simplify the ratio by canceling out common terms:
    a(m+1)/am=(2m+2)(2m+1)(2m)!((m+1)2m+2)/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2m+2)(2m+1)(2m)!}{((m+1)^{2m+2})} / \frac{(2m)!}{(m^{2m})}\right|
    a(m+1)/am=(2m+2)(2m+1)(m+1)2m2m((m+1)2m)|a_{(m+1)}/a_m| = \left|\frac{(2m+2)(2m+1)}{(m+1)^{2}} \cdot \frac{m^{2m}}{((m+1)^{2m})}\right|
    a(m+1)/am=(2m+2)(2m+1)(m+1)2m+2|a_{(m+1)}/a_m| = \left|\frac{(2m+2)(2m+1)}{(m+1)^{2m+2}}\right|Now, we simplify the expression further and take the limit as mm approaches infinity:
    a(m+1)/am=4m2+6m+2(m+1)2m+2|a_{(m+1)}/a_m| = \left|\frac{4m^2 + 6m + 2}{(m+1)^{2m+2}}\right|
    As mm approaches infinity, the highest power of mm in the numerator is m2m^2, and in the denominator, it is a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|00, which grows much faster than m2m^2. Therefore, the limit of this ratio as mm approaches infinity is a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|33.Since the limit of a(m+1)/am|a_{(m+1)}/a_m| as mm approaches infinity is a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|33, which is less than a(m+1)/am=(2(m+1))!((m+1)2(m+1))/(2m)!(m2m)|a_{(m+1)}/a_m| = \left|\frac{(2(m+1))!}{((m+1)^{2(m+1)})} / \frac{(2m)!}{(m^{2m})}\right|77, the ratio test tells us that the series converges.Although we have established that the series converges, we do not have a simple expression for the sum. The value of the sum would likely require numerical methods or special functions to approximate.

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