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The sum of the first four terms of an A.P. is 56. The sum of the last four terms is 112. If its first term is 11, then find the number of terms.

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The correct Answer is:
11
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NCERT TAMIL-SEQUENCES AND SERIES-Miscellaneous Exercise On Chapter 9
  1. The sum of three numbers in G.P. is 56. If we subtract 1, 7, 21 from t...

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  2. A G.P. consists of an even number of terms. If the sum of all the term...

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  3. The sum of the first four terms of an A.P. is 56. The sum of the last ...

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  4. If (a+bx)/(a-bx)=(b-cx)/(b-cx)=(c+dx)/(c-dx)( x ne 0) then show that ...

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  5. Let S be the sum, P the product and R the sum of reciprocals of n term...

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  6. The p^(th), q^(th) and r^(th) terms of an A.P. are a, b, c, respectiv...

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  7. If a(1/b + 1/c), b(1/c + 1/a), c(1/a + 1/b) are in A.P., prove that a,...

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  8. If a, b, c, d are in G.P, prove that (a^n + b^n), (b^n + c^n), (c^n +...

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  9. If a and b are the roots of x^2 – 3x + p = 0 and c, d are roots of x^...

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  10. The ratio of the A.M. and G.M. of two positive numbers a and b, is m :...

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  11. If a, b, c are in A.P., b, c, d are in G.P. and 1/c,1/d,1/e are in A.P...

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  12. Find the sum of the following series up to n terms: (i) 5+55+555+......

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  13. Find the 20^(th) term of the series 2 xx 4 + 4 xx 6 + 6 xx 8 + ... + ...

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  14. Find the sum of the first n terms of the series: 3+ 7 +13 +21 +31 +......

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  15. If S1, S2, S3 are the sum of first n natural numbers, their squares a...

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  16. Find the sum of the following series up to n terms: 1^3/1+(1^3+2^3)/...

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  17. Show that (1 xx 2^(2) + 2 xx 3^(2) + ... +n xx (n + 1)^(2))/(1^(2) xx ...

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  18. A farmer buys a used tractor for Rs 12000. He pays Rs 6000 cash and ag...

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  19. Shamshad Ali buys a scootor for Rs 22000. He pays Rs 4000 cash and agr...

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  20. A person writes a letter to four of his friends. He asks each one of t...

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