Question

if the sum of 'n' terms of arithmetic progession An(square)+Bn+C.Then what is value of 'C'??

Answer 1

we know n term of arithmetic sum=n/2{2a+(n-1) d}--------(1)
where a is first term
d is common difference
now
Sn=an+n^2d/2-nd/2 (from (1)
=(a-d/2)n+d/2.n^2+0
campare this with An^2+Bn+C
you find C=0