Question
Thu September 03, 2009 By: Khushal Gupta

A.P. plzzzz hurry

Expert Reply
Thu September 03, 2009

The extra subscript 1 and 2 refers to the first and second AP respectively.

For example, (Sn)1 = sum of n terms for 1st AP, and so on.

(Sn)1 =n(2a1+(n-1)d1)/2

(Sn)2 =n(2a2+(n-1)d2)/2

(Sn)1/(Sn)2 = (7n+1)/(4n+27) = (2a1+(n-1)d1)/(2a2+(n-1)d2)

Taking n = 9,

 64/63 = (2a1+8d1)/(2a2+8d2) = (a1+4d1)/(a2+4d2

(a5)1 = a1+4d1

(a5)2 = a2+4d2

(a5)1/(a5)2 = (a1+4d1)/(a2+4d2) = 64/63

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