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

If `(1 + x - 2 x^(2))^(6) = 1 + C_(1) x + C_(2) x^(2) + C_(3) x^(3) + …+ C_(12) x^(12)`,
then the value of `C_(2) + C_(4) + C_(6) + …+ C_(12)` is

A

30

B

32

C

31

D

none of these

Text Solution

AI Generated Solution

The correct Answer is:
To find the value of \( C_2 + C_4 + C_6 + \ldots + C_{12} \) from the expansion of \( (1 + x - 2x^2)^6 \), we can follow these steps: ### Step 1: Write the expression We start with the expression: \[ (1 + x - 2x^2)^6 \] ### Step 2: Substitute \( x \) with \( -x \) Next, we will substitute \( x \) with \( -x \): \[ (1 - x - 2x^2)^6 \] ### Step 3: Set up the equations Now we can express both expansions: 1. \( (1 + x - 2x^2)^6 = 1 + C_1 x + C_2 x^2 + C_3 x^3 + \ldots + C_{12} x^{12} \) (Equation 1) 2. \( (1 - x - 2x^2)^6 = 1 - C_1 x + C_2 x^2 - C_3 x^3 + \ldots + C_{12} x^{12} \) (Equation 2) ### Step 4: Add the two equations Adding Equation 1 and Equation 2: \[ (1 + x - 2x^2)^6 + (1 - x - 2x^2)^6 = 2 + 2C_2 x^2 + 2C_4 x^4 + \ldots + 2C_{12} x^{12} \] The terms with odd powers of \( x \) cancel out. ### Step 5: Evaluate at \( x = 1 \) Now, we evaluate the left-hand side at \( x = 1 \): \[ (1 + 1 - 2)^6 + (1 - 1 - 2)^6 = 0 + (-2)^6 = 64 \] Thus, we have: \[ 64 = 2 + 2(C_2 + C_4 + C_6 + \ldots + C_{12}) \] ### Step 6: Solve for the sum of coefficients Rearranging gives: \[ 64 - 2 = 2(C_2 + C_4 + C_6 + \ldots + C_{12}) \] \[ 62 = 2(C_2 + C_4 + C_6 + \ldots + C_{12}) \] Dividing by 2: \[ C_2 + C_4 + C_6 + \ldots + C_{12} = 31 \] ### Final Answer Thus, the value of \( C_2 + C_4 + C_6 + \ldots + C_{12} \) is: \[ \boxed{31} \]
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OBJECTIVE RD SHARMA ENGLISH-BINOMIAL THEOREM AND ITS APPLCIATIONS -Exercise
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  2. Find the coefficient of x^4 in the expansion of (1+x+x^2+x^3)^(11)dot

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

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  4. If the coefficient of the middle of term in the expansion of (1+x)^(2n...

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  5. If a1,a2, a3, a4 be the coefficient of four consecutive terms in the e...

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  6. The coefficient of x^r[0lt=rlt=(n-1)] in the expansion of (x+3)^(n-1)+...

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  7. If (1-x+x^2)^n=a0+a1x+a2x^2+ .........+a(2n)x^(2n),\ find the value o...

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  8. The coefficient of x^m in (1+x)^m +(1+m)^(m+1) +...+(1+x)^n ,m≤n is

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  9. the coefficient of x^(7) in (ax - b^(-1) x^(-2))^(11) is

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  10. Find the coefficient of x^5 in the expansion of (1+x^2)^5(1+x)^4.

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  11. Find the greatest term in the expansion of sqrt(3)(1+1/(sqrt(3)))^(20)...

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  12. If T0,T1, T2, ,Tn represent the terms in the expansion of (x+a)^n , t...

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  13. about to only mathematics

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  14. If the coefficients of three consecutive terms in the expansion of (1+...

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  15. The second, third and fourth terms in the binomial expansion (x+a)^na...

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  16. The value of tan75

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  17. If the coefficients of the (2r+4)t h ,(r+2)t h term in the expansion o...

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  18. Write the middle term in the expansion of (x+1/x)^(10)dot

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  19. The 14^(th) term from the end in the expansion of (sqrt(x ) - sqrt(y)...

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  20. If [x] denotes the greatest less than or equal to x and F = R - [R]...

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