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If an AP a7=9 and a1a2a7 is least , then...

If an AP `a_7=9` and `a_1a_2a_7` is least , then common difference is

A

13/20

B

23/20

C

33/20

D

43/20

Text Solution

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The correct Answer is:
C
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PATHFINDER-PROGRESSION AND SERIES -QUESTION BANK
  1. If the sum of the first 2n terms of the AP 2,5,8.....is equal to the s...

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  2. If xin R , the number 5^(1+x)+5^(1-x),a/2,25^x+25^-xform an AP , then ...

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  3. If an AP a7=9 and a1a2a7 is least , then common difference is

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  4. Consider an infinite geometric series with first term a and common rat...

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  5. The value of a^(logb(x))=(where, a=0.2,b=sqrt5), x=(1/4+1/8+1/16+........

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  6. If a,b,c are in HP and agtcgt0, then 1/(b-c)-1/(a-b).

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  7. Let the positive numbers a,b,c,d be in AP , Then abc, abd,acd,bcd are

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  8. If a,b,c are in HP , thn the value of (b+a)/(b-a)+(b+c)/(b-c) is

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  9. If x1gt0,i=1,2.....50 and x1+x2+.....x50=50 then the minimum value of ...

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  10. If three positive real number a,b,c are in AP with abc =4 , then the m...

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  11. The sum of 10 terms of the series 0.7+.77+.777+.... is

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  12. Find the sum of the series upto n terms 1.3.5+3.5.7+5.7.9+....

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  13. Find the sum of first n terms of the series 3/1^2+5/(1^2+2^2)+7/(1^2+2...

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  14. If the sum to infinity to the series 1+4x+7x^2+10x^3+..... is 35/16 th...

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  15. Consider an AP with first term a and the common difference 'd' Let Sk...

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  16. If p,q,r are three positive real number are in AP , then the roots of ...

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  17. The solution of the equation (8)^((1+[cosx absdivcos^2xabsdiv cos^3x]d...

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  18. If (1+x)(1+x^2)(1+x^4)....(1+x^128)=sum(r=0)^nx^r then n is

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  19. If angt1 for all ninN,then log(a2)a1+log(a3)a2+.....+log(an)a(n-1)+log...

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  20. Let Sk=underset(nrarrinfty)limsum(i=0)^n1/(k+1)^i. Then sum(k=1)^nkSk...

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