Evaluate: $~~\displaystyle\sum\limits_{k=1}^{8}{\left(-4 k^2+6k \right)}\,$.
[[☃ input-number 1]]
For reference:
$\qquad\displaystyle\sum\limits_{i=1}^{n}{i^2=\frac{n\left( n+1 \right)(2n+1)}{6}}$
$\qquad\displaystyle\sum\limits_{i=1}^{n}{i=\frac{n\left( n+1 \right)}{2}}$