Question

if the sequence is
2,15,52,125,246....
find the nth term expression
and sum of the nth terms

Answer 1

see related questions below.

Answer 2

i reposted these because i don notn know what u mean by
ur very last step 4th polynomial something

Answer 3

take a look at the sums of powers of integers:

1+2+3+... = n(n-1)/2 (2nd degree)
1^2+2^2+3^2+... = n(n+1)(2n+1)/6 (3rd degree)
1^3+2^3+... = n^2(n+1)^2/4 (4th degree)

The sum of kth powers of integers is a k+1 degree polynomial.