Question

find the sum...........​

Answer 1

Answer:

Square them and add them

Answer 2

Answer:

Step-by-step explanation:

nth term = n(n+1)^2 = n^3 + 2n^2 + n

sum = n^2(n+1)^2/4 +2n(n+1)(2n+1)/6  + n(n+1)/2

= n^2(n+1)^2/4 +n(n+1)(2n+1)/3  + n(n+1)/2

knowing that sum of n n(n+1)/2 sum of squares n(n+1)(2n+1)/6 and sum of cubes