IIT JEE , AIEEE Forum - Mathematics , Algebra - the ratio of the sum of n terms of two a.p.'s is (7n+1):(4n+27) the ratio of the mth terms

bhompu

the ratio of the sum of n terms of two a.p.'s is (7n+1):(4n+27) the ratio of the mth terms

akshay.gupta

u r dropping...n this is ur Q. ???...relli strange!

its a X level Q.

iitkgp_bipin

Let the sum for both AP's be :

(n/2){2(4) + (n-1)(7)} and (n/2){2(31/2) + (n-1)(4)}

Both of them are expressed in the form of (n/2)(2a + (n-1)d)

so their mth terms are 4 + (m-1)7 and 31/2 + (m-1)4

7m-3 and 4m + 23/2

so their ratio = (7m-3) / (4m + 23/2) = (14m - 6) / (8m + 23)

ganapathi1810

ALREADY I SEND

SIMPLEST METHOD

SIXTH SEPTEMBER.

gurl

simplest trick............
write the problem in equation form...

n/2[2a+(n-1)d]/n/2[2A+(n-1)D] = 7n+1/4n+27....

now everywhere replace n by 2m-1....and u'll get the answer.......

14m-6/8m+23

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