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Let a(1) , a(2) , a(3) , "……………" be term...

Let `a_(1) , a_(2) , a_(3) , "……………"` be terms of an A.P. If `(a_(1) + a_(2) + "........" + a_(p ))/(a_(1) + a_(2) + "......." + a_(q)) = ( p ^(2))/( q^(2)) , p cancel(=)q`, then `( a_(6))/( a_(21))` equals `:`

A

`(41)/(11)`

B

`(7)/(2)`

C

`(2)/(7)`

D

`(11)/(41)`

Text Solution

Verified by Experts

The correct Answer is:
D
`:.((p)/(2)[2a_(1)+(p-1)d])/((q)/(2)[2a_(1)+(q-1)d])=(p^(2))/(q^(2))`
`implies (2a_(1)+(p-1)d)/(2a_(1)+(q-1)d)=(p)/(q)implies (a_(1)+((p-1)/(2))d)/(a_(1)+((q-1)/(2))d)=(p)/(q)`
For `(a_(6))/(a_(21)),p=11" and " q=41 implies(a_(6))/(a_(21))=(11)/(41)`.
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