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If the sum to infinity of the series 1+2...

If the sum to infinity of the series `1+2r+3r^2+4r^3+` is 9/4, then value of `r` is (a)`1//2` b. `1//3` c. `1//4` d. none of these

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CENGAGE PUBLICATION-SEQUENCES AND SERIES-All Questions
  1. Let S=4/(19)+(44)/(19^2)+(444)/(19^3)+ u ptooo . Then s is equal to a....

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  2. If Hn=1+1/2+...+1/ndot , then the value of Sn=1+3/2+5/3+...+(99)/(50) ...

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  3. If the sum to infinity of the series 1+2r+3r^2+4r^3+ is 9/4, then val...

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  4. The sum o f series 1+4/5+7/(5^2)+(10)/(5^3)+oo is a. 7//16 b. 5//16 ...

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  5. The sum 20 terms of a series whose rth term is given by Tr=(-1)^r((r^2...

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  6. Consider the sequence 1,2,2,4,4,4,4,8,8,8,8,8,8,8,8,... Then 1025th te...

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  7. If the first term of an A.P. is – 18 and its 10th term is zero, then f...

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  8. Suppose that F(n + 1) =(2F(n) + 1)/2 for n = 1,2,3,,,, and F(1) = 2. T...

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  9. If the numbers n – 2, 4n – 1 and 5n + 2 are in A.P., find the value of...

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  10. The first and the last terms of an A.P. are 17 and 350 respectively. I...

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  11. If a ,b ,and c are in A.P., then a^3+c^3-8b^3 is equal to (a).2a b c (...

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  12. The number of terms of an A.P. is even. The sum of the odd terms is 24...

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  13. The first term of an A.P. is 5, the last term is 45 and the sum is 400...

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  14. If the sum of m terms of an A.P. is the same as the sum of its n terms...

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  15. Find the 20th term of the A.P. whose 7th term is 24 less than the 11th...

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  16. About 150 workers were engaged to finish a piece of work in a certain ...

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  17. in a G.P (p+q)th term = m and (p-q) th term = n , then find its p th t...

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  18. The sum of three numbers in A.P. is 3 and their product is – 35. Find ...

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  19. Find the sum of first 51 terms of the A.P. whose second and third term...

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  20. Let S1 , S2,,,,, be squares such that for each n ge 1 the length of a ...

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