Let XXX be discrete with PMF P(X=k)=ck(k+1)P(X=k) = \frac{c}{k(k+1)}P(X=k)=k(k+1)c for k=1,2,3,…k = 1, 2, 3, \ldotsk=1,2,3,…. Find ccc.
1
2
12\frac{1}{2}21
Does not exist