Question

what is the formula for sum of the arithmetic progression and what is the formula for sum of the first N positive integers

Answer 1

an=a+(n-1)d


sn=n/2(a+l)
or
sn=n/2[2a+(n-1)d]

Answer 2

sn=n/2{2a+(n-1)d} 0r there is another formula that is. sn=n/2{a+al} where al is the last term of an ap