Question

find the sum of AP 2,7,12...,to 10terms

Answer 1

Sn=n/2(2a+(n-1)d)
a=2
d=5
n=10
S10=5(4+45)
=5*50
=250

Answer 2

Here is your solution

Given :-

AP 2,7,12...to 10th term

N= 10

we know that

Sn = n/2 + 2a (n-1)d

s10 = 10/2 +2×2 (10-1)5
s10= 5 +4×9×5
s10 = 5+180
s10= 185

The sum of 10 term is 185.

Hope it helps you