Question

How do you find the sum given `Sigma k(k-2)` from k=3 to 6?

Answer 1

`sum_(k=3)^(k=6) k(k-2) = 50`

Explanation:

`sum_(k=3)^(k=6) k(k-2) = 3(3-2) + 4(4-2) + 5(5-2) + 6(6-2)`
`:. sum_(k=3)^(k=6) k(k-2) = 3(1) + 4(2) + 5(3) + 6(4)`
`:. sum_(k=3)^(k=6) k(k-2) = 3 + 8 + 15 + 24`
`:. sum_(k=3)^(k=6) k(k-2) = 50`