Question

find the sum of first 10natural numbers of an A.P

Answer 1

Answer:

we know that,

first 10 natural numbers are 1,2,.......,10

Clearly these numbers are in AP of common difference d=1

then sum of n terms in AP is

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

here, n = total number of terms

a= first term

d= common difference

then, S = 10/2 [2(1) +(10-1)(1)]

= 5[2+9]

= 5(11)

S = 55.

Therefore, the sum of first 10 natural numbers is 55.