Question

sum (k^2-4),k=0..14
the answer is 955
just give me the steps please

Answer 1

14
Σ (k^2-4)
k=0

Answer 2

\[\sum _{k=0}^n k^2=\frac{1}{6} n (n+1) (2 n+1)\\
\sum _{k=0}^{14} k^2=\frac{1}{6} n (n+1) (2 n+1)=1015\\
1015 - 15 (4)= 955
\]

Answer 3

\[\sum_{k=0}^{14} (k^2-4)=\sum_{k=0}^{14} k^2 - \sum_{k=0}^{14} 4\]\[=\sum_{k=0}^{14}k^2 -15(4)\]\[={14(14+1)(2(14)+1) \over 6} -60=1015-60=955\]