Question

If the ratio of the sum of first n terms of two ap is (7n+1):(4n+27). Find the ratio of thire m terms

Answer 1

a1+ a2 + a3 +........an = 7n+1
_______________ ____
A1+ A2 +A3+........An 4n+27

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

2a+(n-1)d. 7n+1
_______. = ____
2A+(n-1)D. 4n+27

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

a+(n-1)/2d. 7n+1
______. = ____. --------(1)
A+(n-1)/2D. 4n+27
put (n-1)/2 =m-1 -----------(2)
n-1. =2m-2
n=2m-2+1
n=2m-1 ----------------(3)
put(2) and (3) in (1)
a+(m-1)d. 7(2m-1)+1
______. =. _______
A+(m-1)D. 4(2m-1)+27

am. 14m-7+1
__. =. ______
Am. 8m-4+27

am. 14m-6
__. = _____
Am. 8m+23