Question

If the sum of first m terms of an ap is am 2+bm. Find the 25th term

Answer 1

Step-by-step explanation:

nth term of an A.P = a+(n-1)d

Sum of m terms of an A.P = m/2 {2a+(m-1)d }

=am^2+bm

25th term = a+(25-1)d = a+(24)d

First term = a(1)^2 + b(1) = a+b

Sum of 1st two terms = a(2)^2 + 2b = 4a+2b

Second term = 4a+2b - (a+b) = 3a+b

Common difference = 3a+b - (a+b) = 2a

Hence 25th term = a+24d = a+b+24(2a) = a+b+48a = 49a+b