Question

The sum of the first 10 terms of the A.P. 3, 4, 5, 6, .... is

Answer 1

Let 10 is term of a. p then Tn=10 put the formula a+(n-1)d=10.a=3 d=1 then 3+(n-1)1=10 4/10=2/5 is the answer

Answer 2

Take Sn=n/2[2a(n-1)d]