Formula used:
Let f and g be real valued functions defined on the same nonnegative integers, with g(n)≥0 for every integer n≥r, where r is positive real number.
Then,
f is of order g, written f(n) is Θ(g(n)), if and only if, there exist positive real numbers A,B and k≥r such that
Ag(n)≤f(n)≤Bg(n) for every integer k≥a.
The summation of first n terms of an arithmetic progression is given by
Sn=n2(a+l)
Where, n= number of termsa= first terml= last termSn= simmation of n terms.
Calculation:
The given series 1+2+3+