Question

find the sum of
(ii)the first n positive integers​

Answer 1

Answer:

First n positive integers are 1,2,...,n.\

They are in A.P. with a=1,d=1

Sum will be 1+2+...+n=  n/2 [2a+(n−1)d]

n/2 [2(1)+(n−1)1]

n/2[2+n−1]

n(n+1)/2

Step-by-step explanation:

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