Question

if a and l be the first and last term of A.P. and S be the sum of its all terms then it's common difference is?

Answer 1

Hello!


First term = a

Last term = l

Sum = S


According to Question,

S = n/2 [2a + (n - 1) d]

2S = 2an + n (n - 1) d

2S = 2an + n²d - nd

2S - 2an = d (n² - n)

Therefore, d = (2S - 2an) / n² - n


I hope it helped.


Thank You!