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If `a ,b ,c ,d ,e ,f` are A.M.s between 2 and 12, then find the sum `a+b+c+d+e+fdot`

A

14

B

42

C

84

D

none of these

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The correct Answer is:
B
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OBJECTIVE RD SHARMA ENGLISH-SEQUENCES AND SERIES-Exercise
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  2. Let the sum of n, 2n, 3n terms of an A.P. be S1,S2and S3, respectively...

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  3. If a ,b ,c ,d ,e ,f are A.M.s between 2 and 12, then find the sum a+b+...

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  4. If a, b, c are in G.P, then loga x, logb x, logc x are in

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  5. If x,y,z are in H.P then the value of expression log(x+z)+log(x-2y+z)=

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  6. If a,b,c,d are in H.P., then ab+bc+cd is equal to

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  7. The sum of i-2-3i+4 up to 100 terms, where i=sqrt(-1) is 50(1-i) b. 2...

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  8. (i) a , b, c are in H.P. , show that (b + a)/(b -a) + (b + c)/(b - c)...

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  9. If a,b,c are in H.P, then

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  10. If a , b, c, be in A.P. , b, c,d in G.P. and c.d.e.in H.P., then prov...

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  11. If (a+b)/(1-ab),b,(b+c)/(1-bc) are in AP, then a,(1)/(b),c are in

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  12. If the sum of n terms of an A.P is cn (n-1)where c ne 0 then the sum o...

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  13. Sum of the first p, q and r terms of an A.P are a, b and c, respectiv...

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  14. If Sn=1/1^3 +(1+2)/(1^3+2^3)+...+(1+2+3+...+n)/(1^3+2^3+3^3+...+n^3) T...

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  15. If a,b and c are in A.P. a,x,b are in G.P. whereas b, y and c are also...

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  16. If log(x+z)+log(x-2y+z)=2log(x-z)," then "x,y,z are in

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  17. If (1)/(a)+(1)/(c)+(1)/(a-b)+(1)/(c-b)=0, than prove that a,b,c are in...

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  18. If arithmetic mean of two positive numbers is A, their geometric mean ...

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  19. If (1-p)(1+3x+9x^2+27 x^3+81 x^4+243 x^5)=1-p^6,p!=1 , then the value ...

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  20. If a, b, c are in G.P, then loga x, logb x, logc x are in

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