Question

If the ratio of the sum of the first n terms of two AP is 7n+1 : 4n+27 then find the ratio of the 9th term​

Answer 1

Step-by-step explanation:

dekh ko bhai yeh galat baat hai kyuki apne se kosis karo sab ban jayega kuch hard nhi hots koi bhi sawal

Answer 2

SN1/SN2 = n/2{2a + (n - 1)d} / n/2{2A + (n - 1)D}

SN is used here to denote sum of AP

(7n + 1) / (4n + 27) = {2a + (n - 1)d} / {2A + (n - 1)D}

let n be 17( for every question like this , always take n double of that term which you have to find and subtract 1 from it)

(7×17 + 1) / (4×17 + 27) = {2a + (17 - 1)d} / {2A + (17 - 1)D}

120/95 = (2a + 16d) / (2A + 16D)

120/95 = 2(a + 8d) / 2(A + 8D)

120/95 = (a + 8d) / (A + 8D)

we know that 9th term can be written as 'a + 8d'

24/19 = (a+8d) / (A+8D)

hence the ratio is 24:19

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