The ratio of the sums of m and n terms of an A.P. is m2 : n2. Show that the ratio of mth and nth term is (2m – 1) : (2n – 1).
Let a and d be the first term and common difference of the A.P.
Given,
Sum of m terms of A.P. = Sm
Sum of n terms of A.P. = Sn
Putting m = 2m – 1 and n = 2n – 1 in the above equation
⇒
∴ Ratio of mth and nth term is (2m – 1) : (2n – 1).