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In the expansion of (1+x)^(50), find the...

In the expansion of `(1+x)^(50),` find the sum of coefficients of odd powers of `x`.

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To find the sum of the coefficients of the odd powers of \( x \) in the expansion of \( (1+x)^{50} \), we can follow these steps: ### Step 1: Understand the Binomial Expansion The binomial expansion of \( (1+x)^n \) is given by: \[ (1+x)^n = \sum_{k=0}^{n} \binom{n}{k} x^k \] For our case, \( n = 50 \), so: \[ (1+x)^{50} = \sum_{k=0}^{50} \binom{50}{k} x^k \] ### Step 2: Identify Coefficients of Odd Powers We need to find the sum of the coefficients of odd powers of \( x \). The odd powers in this expansion are \( x^1, x^3, x^5, \ldots, x^{49} \). The coefficients corresponding to these powers are \( \binom{50}{1}, \binom{50}{3}, \binom{50}{5}, \ldots, \binom{50}{49} \). ### Step 3: Use the Binomial Theorem with \( x = 1 \) and \( x = -1 \) To find the sum of the coefficients of odd powers, we can evaluate the polynomial at \( x = 1 \) and \( x = -1 \). 1. **Evaluate at \( x = 1 \)**: \[ (1 + 1)^{50} = 2^{50} \] This gives us the sum of all coefficients: \[ \sum_{k=0}^{50} \binom{50}{k} = 2^{50} \] 2. **Evaluate at \( x = -1 \)**: \[ (1 - 1)^{50} = 0 \] This gives us the alternating sum of the coefficients: \[ \sum_{k=0}^{50} (-1)^k \binom{50}{k} = 0 \] ### Step 4: Set Up the Equations From the evaluations: - Let \( S \) be the sum of the coefficients of odd powers: \[ S = \binom{50}{1} + \binom{50}{3} + \binom{50}{5} + \ldots + \binom{50}{49} \] - Let \( T \) be the sum of the coefficients of even powers: \[ T = \binom{50}{0} + \binom{50}{2} + \binom{50}{4} + \ldots + \binom{50}{50} \] From our previous evaluations, we have: 1. \( S + T = 2^{50} \) 2. \( T - S = 0 \) ### Step 5: Solve the Equations From \( T - S = 0 \), we can deduce that: \[ T = S \] Substituting \( T \) in the first equation gives: \[ S + S = 2^{50} \implies 2S = 2^{50} \implies S = 2^{49} \] ### Final Answer Thus, the sum of the coefficients of the odd powers of \( x \) in the expansion of \( (1+x)^{50} \) is: \[ \boxed{2^{49}} \]

To find the sum of the coefficients of the odd powers of \( x \) in the expansion of \( (1+x)^{50} \), we can follow these steps: ### Step 1: Understand the Binomial Expansion The binomial expansion of \( (1+x)^n \) is given by: \[ (1+x)^n = \sum_{k=0}^{n} \binom{n}{k} x^k \] For our case, \( n = 50 \), so: ...
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