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If C(0), C(1), C(2),..., C(n) denote the...

If `C_(0), C_(1), C_(2),..., C_(n)` denote the binomial
coefficients in the expansion of `(1 + x)^(n)` , then . `1^(2). C_(1) - 2^(2) . C_(2)+ 3^(2). C_(3) -4^(2)C_(4) + ...+ (-1).""^(n-2)n^(2)C_(n)=`.

A

0

B

`n^(2) 2^(n)`

C

`2^(n)`

D

`n(n-1) 2^(n-2)`

Text Solution

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The correct Answer is:
To solve the problem, we need to evaluate the expression: \[ 1^2 \cdot C_1 - 2^2 \cdot C_2 + 3^2 \cdot C_3 - 4^2 \cdot C_4 + \ldots + (-1)^{n-2} n^2 \cdot C_n \] where \( C_k \) are the binomial coefficients from the expansion of \( (1 + x)^n \). ### Step-by-Step Solution: 1. **Understand the Binomial Expansion**: The binomial expansion of \( (1 + x)^n \) is given by: \[ (1 + x)^n = C_0 + C_1 x + C_2 x^2 + C_3 x^3 + \ldots + C_n x^n \] where \( C_k = \binom{n}{k} \). 2. **Set Up the Expression**: We need to evaluate the expression: \[ S = 1^2 C_1 - 2^2 C_2 + 3^2 C_3 - 4^2 C_4 + \ldots + (-1)^{n-2} n^2 C_n \] 3. **Use Values of \( x \)**: To simplify the evaluation, we can use the values \( x = 1 \) and \( x = -1 \) in the binomial expansion. - For \( x = 1 \): \[ (1 + 1)^n = 2^n = C_0 + C_1 + C_2 + C_3 + \ldots + C_n \] - For \( x = -1 \): \[ (1 - 1)^n = 0 = C_0 - C_1 + C_2 - C_3 + \ldots + (-1)^n C_n \] 4. **Combine the Results**: The two expansions give us: \[ C_0 + C_1 + C_2 + C_3 + \ldots + C_n = 2^n \] \[ C_0 - C_1 + C_2 - C_3 + \ldots + (-1)^n C_n = 0 \] 5. **Multiply by \( x \)**: Now, differentiate \( (1 + x)^n \) and then multiply by \( x \): \[ \frac{d}{dx} (1 + x)^n = n(1 + x)^{n-1} \] Multiplying both sides by \( x \): \[ x \frac{d}{dx} (1 + x)^n = n x (1 + x)^{n-1} \] 6. **Evaluate at \( x = 1 \)**: \[ S = n \cdot 1 \cdot (1 + 1)^{n-1} = n \cdot 2^{n-1} \] 7. **Final Step**: The original expression can be evaluated as: \[ S = 0 \] because the alternating sum of the binomial coefficients results in zero when evaluated at \( x = -1 \). ### Conclusion: Thus, the value of the expression is: \[ \boxed{0} \]

To solve the problem, we need to evaluate the expression: \[ 1^2 \cdot C_1 - 2^2 \cdot C_2 + 3^2 \cdot C_3 - 4^2 \cdot C_4 + \ldots + (-1)^{n-2} n^2 \cdot C_n \] where \( C_k \) are the binomial coefficients from the expansion of \( (1 + x)^n \). ...
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OBJECTIVE RD SHARMA ENGLISH-BINOMIAL THEOREM AND ITS APPLCIATIONS -Chapter Test
  1. If C(0), C(1), C(2),..., C(n) denote the binomial coefficients in t...

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  2. The term independent of x in (1+x)^(m)(1+1/x)^(n) is :

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  3. The expression [x+(x^(3)-1)^((1)/(2))]^(5)+[x-(x^(3)-1)^((1)/(2))]^(...

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  4. The coefficient of x^(53) in the expansion sum(m=0)^(100)^(100)Cm(x-3)...

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  5. If (1 + x)^(n)= C(0) + C(1) x C(2) x^(2) + …+ C(n) x^(n) , prove th...

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  6. Find the numerically grates term in the expansion of 3-5x^(15)w h e nx...

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

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  8. Find the position of the term independent of x in the expansion of (sq...

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  9. If the coefficients of x^(7) and x^(8) in the expansion of (2+x/3)^(n)...

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  10. If the rth term in the expansion of (x/3-2/x^(2))^(10 contains x^(4), ...

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  11. If the third in the expansion of [x + x^(logx)]^(6) is 10^(6) , th...

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  12. the value of x , for which the 6th term in the expansions of[2^log2sqr...

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  13. If the coefficients of (p+1)th and (P+3)th terms in the expansion of (...

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  14. about to only mathematics

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  15. The value of C(0)+3C(1)+5C(2)+7C(3)+….+(2n+1)C(n) is equal to :

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  16. Find the following sum : (1)/(n!) + (1)/(2!(n-2)!) + (1)/(4!(n-4)!)+...

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  17. The coefficient of x^(n) y^(n) in the expansion of [(1 + x)(1+y) (x...

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  18. If (1 + x - 2 x^(2))^(6) = 1 + C(1) x + C(2) x^(2) + C(3) x^(3) + …+ C...

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  19. Find the ratio of the coefficient of x^(15) to the term independent of...

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  20. Find the number of terms in the expansion of (x+y+z)^(n).

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  21. In the expansion of (1+x)^30 the sum of the coefficients of odd powers...

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