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If the coefficients of (r-5)^(t h) and (...

If the coefficients of `(r-5)^(t h)` and `(2r-1)^(t h)` terms in the expansion of `(1+x)^(34)` are equal, find `rdot`

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To solve the problem, we need to find the value of \( r \) such that the coefficients of the \( (r-5)^{th} \) and \( (2r-1)^{th} \) terms in the expansion of \( (1+x)^{34} \) are equal. ### Step-by-step Solution: 1. **Understanding the Coefficient of Terms in Binomial Expansion**: The coefficient of the \( k^{th} \) term in the expansion of \( (1+x)^n \) is given by \( \binom{n}{k-1} \). Therefore, the coefficient of the \( (r-5)^{th} \) term is: \[ \text{Coefficient of } (r-5)^{th} = \binom{34}{(r-5)-1} = \binom{34}{r-6} \] Similarly, the coefficient of the \( (2r-1)^{th} \) term is: \[ \text{Coefficient of } (2r-1)^{th} = \binom{34}{(2r-1)-1} = \binom{34}{2r-2} \] 2. **Setting the Coefficients Equal**: Since the coefficients are equal, we can set up the equation: \[ \binom{34}{r-6} = \binom{34}{2r-2} \] 3. **Using the Property of Binomial Coefficients**: We can use the property that \( \binom{n}{k} = \binom{n}{n-k} \). Thus, we can rewrite the right-hand side: \[ \binom{34}{2r-2} = \binom{34}{34 - (2r-2)} = \binom{34}{36 - 2r} \] Therefore, we have: \[ \binom{34}{r-6} = \binom{34}{36 - 2r} \] 4. **Setting the Indices Equal**: From the equality of binomial coefficients, we can equate the indices: \[ r - 6 = 36 - 2r \] 5. **Solving for \( r \)**: Rearranging the equation gives: \[ r + 2r = 36 + 6 \] \[ 3r = 42 \] \[ r = \frac{42}{3} = 14 \] ### Final Answer: Thus, the value of \( r \) is: \[ \boxed{14} \]

To solve the problem, we need to find the value of \( r \) such that the coefficients of the \( (r-5)^{th} \) and \( (2r-1)^{th} \) terms in the expansion of \( (1+x)^{34} \) are equal. ### Step-by-step Solution: 1. **Understanding the Coefficient of Terms in Binomial Expansion**: The coefficient of the \( k^{th} \) term in the expansion of \( (1+x)^n \) is given by \( \binom{n}{k-1} \). Therefore, the coefficient of the \( (r-5)^{th} \) term is: \[ \text{Coefficient of } (r-5)^{th} = \binom{34}{(r-5)-1} = \binom{34}{r-6} ...
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CENGAGE ENGLISH-BINOMIAL THEOREM-Concept Application Exercise 8.1
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