For question 1d my solution is this..or this is how i understood what the question was asking.
#Triangle numbers and summations
desert citrus
but what i dont understand from this question is how t_k equals n(n+1)(n+2)/6
isnt that supposed to be what the summation of k^2 looks like in closed form?
but this triangle number is k(k+1)/2 not k^2 so does that mean I need to prove that k(k+1)/2 = k^2?
distant gorge
isnt that supposed to be what the summation of k^2 looks like in closed form?
...no? You have the closed form for the nth partial sum of k^2 written right there...
Like, right at the top of the page.
desert citrus
oh right i didnt see my bad