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7 + 77 + 777 + …. N terms =...

7 + 77 + 777 + …. N terms =

A

`(7n)/(9) - (7)/(81) (1 - (1)/(10^(n)))`

B

`(7(10^(n) - 1))/(9) - (7n)/(81)`

C

`(70(10^(n) - 1))/(81) - (7n)/(9)`

D

none

Text Solution

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The correct Answer is:
A
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DIPTI PUBLICATION ( AP EAMET)-SEQUENCES AND SERIES -EXERCISE
  1. 6 + 66 + 666 + ….n terms =

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  2. The sum to n terms of the series .5 + .55 + .555 + ….. Is

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  3. 7 + 77 + 777 + …. N terms =

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  4. The sum of first 20 terms of the sequence 0.7, 0.77, 0.777,….. Is

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  5. The value of n for which 704 + (1)/(2) (704) + (1)/(4)(704) + ….. Upto...

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  6. The positive integer n for which 2 . 2^(2) + 3 . 2^(3) + 4 . 2^(4) + ....

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  7. (666 …. N digits)^(2) + (888 …. N digits ) =

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  8. If the sum of three numbers in a G.P is 26 and the sum of products two...

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  9. If 0 lt phi lt pi//2 , and x = sum(n = 0)^(infty) cos^(2n) phi, y = su...

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  10. If the sum of three numbers in G.P is 21 and their product is 216, the...

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  11. If the sum of three numbers in G.P is 7/64 and the product of the extr...

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  12. If pth, qth, rth terms of an A.P are a,b,c then a(q - r ) + b(r - p ) ...

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  13. Let S(1),S(2),S(3), …. Are squares such that for each nge1, The lengt...

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  14. In G.P (p + q)th term is m, (p -q)th term is n, then pth terms is

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  15. If 2pth term of a G.P is q^(2) and 2qth term is P^(2) , then (p + q)th...

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  16. If g(1), g(2), g(3) are three geometric means between two positive num...

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  17. What is the G.M. of 6 and 24?

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  18. One of the 5 geometric means between (1)/(3) and 243 is

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  19. If x,y,z are the three geometric means between 6,54, then z =

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  20. IF the A.M and G.M of two numbers are 13 and 12 respectively. Find the...

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