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If the first, second and the last terms of an A.P. are a,b,c respectively, then the sum of the A.P. is

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The correct Answer is:
`((b+c-2a)(a+c))/(2(b-a)`
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CBSE COMPLEMENTARY MATERIAL-SEQUENCES AND SERIES -SECTION-C(SHORT anwer type )
  1. solve: 1 + 6 + 11 + 16 +.........+ x = 148

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  2. The ratio of the sum of n terms of two A.P.'s is (7n-1): (3n +11), fin...

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  3. If the first, second and the last terms of an A.P. are a,b,c respectiv...

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  4. If (b+c-2a)/(a), (c+a-2b)/(b),(a+b-2c)/(a) are in A.P then show that (...

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  5. The product of first three terms of a G.P. is 1000. If 6 added to its ...

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  6. If the continued product of three numbers in G.P. is 216 and the sum o...

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  7. Find the sum to infinity of the series: 1+3/2+5/2^2+7/2^3+..........oo

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  8. if A=1+r^a+r^(2a)+......... up to infinity then express r in terms of ...

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  9. Find the sum of first n terms of the series 0.7 + 0.77 + 0.777 + …..

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  10. "If "x=a+(a)/(r)+(a)/(r^(2))+...oo,y=b-(b)/(r)+(b)/(r^(2))-...oo,"and ...

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  11. The sum of first three terms of a G.P. is 15 and sum of next three ter...

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  12. Prove that 0.0031=7/225 [Hint: 0.031 = 0.03 + 0.001 + 0.0001 +.....Now...

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  13. If a ,\ b\ c are in G.P., prove that the following are also in G.P.: a...

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  14. If a ,\ b\ c are in G.P., prove that the following are also in G.P.: a...

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  15. If a, b, c are in G.P. that the following are also in G.P. sqrt(a),sqr...

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  16. If a, b, c are in A.P. that the following are also in A.P:(i)(1)/(bc),...

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  17. If a,b,c are in A.P. prove that b+c,c+a,a+b are also in A.P.

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  18. If a, b, c are in A.P. then prove that the following are also in A.P:(...

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  19. "If " a^(2), b^(2), c^(2)" are in A.P., prove that "(1)/(b+c),(1)/(c+a...

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  20. Show that 0. 3bar(56) =353/990

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