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If the second term of the expansion `[a^(1/(13))+a/(sqrt(a^(-1)))]^n` is `14 a^(5//2)` , then the value of `(^n C_3)/(^n C_2)` is.

A

4

B

3

C

12

D

6

Text Solution

Verified by Experts

The correct Answer is:
a
We have,
s`""^(n)C_(r) (root(13)(a))^(a-1) ((a)/(sqrt(a^(-1))))^(1) = 14 a^(5//2)`
`rArr na^((n+1)/(13)+(3)/(2)) = 14 a^(5//2) rArr n=14`
`therefore (""^(n)C_(3))/(""^(n)C_(2))=(n-2)/(3) = (14-2)/(3) = 4 [because (""^(n)C_(3))/(""^(n)C_(2))=(n-r+1)/(r)]` s
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OBJECTIVE RD SHARMA ENGLISH-BINOMIAL THEOREM AND ITS APPLCIATIONS -Chapter Test
  1. If the second term of the expansion [a^(1/(13))+a/(sqrt(a^(-1)))]^n is...

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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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