Question 0502d

Sigma Notation

Bottom Limit Handling

Question

It is given that

{f(r) = 2 r + 8}

and

\sum_{r=1}^n f(r) = n^2 + 9 n + 7.

Find an expression for

\displaystyle \sum_{r=13}^{n} f(r).

in the form

{n^2 + Bn + C,}

where

{B}

and

{C}

are constants to be determined.

{B = }

{C = }