SOLUTION: The closed form sum of 12 [ 1^2 * 2 + 2^2 * 3 + ... + n^2 (n+1) ] for n <= 1 is n(n+1)(n+2)(an+b). Find an + b.

Algebra.Com
Question 1177060: The closed form sum of
12 [ 1^2 * 2 + 2^2 * 3 + ... + n^2 (n+1) ]
for n <= 1 is n(n+1)(n+2)(an+b). Find an + b.

Answer by greenestamps(13203)   (Show Source): You can put this solution on YOUR website!


Obviously, from the form of the expression, the statement of the problem is supposed to say that the closed form of the sum is for n >=1 -- not for n <= 1.

There are only two unknowns in the problem -- a and b. So two equations in a and b should be enough to solve the problem.

n=1....

-->

n=2....

-->

a+b=4; 2a+b=7 --> a=3, b=1.

ANSWER: an+b = 3n+1

CHECK for n=3....

12(2(1^)+3(2^2)+4(3^2) = 12(2+12+36) = 600
(3)(4)(5)(3(3)+1) = 600


RELATED QUESTIONS

find the sum of following series:... (answered by Edwin McCravy)
Given three consecutive integers with a sum of four times the second number, write an... (answered by CubeyThePenguin)
Find all integers n for which \frac{n^2 + n + 1}{n - 2 + n^3} is an integer. (answered by CPhill,math_tutor2020)
n!(n+2)=n!+(n+1)! (answered by LinnW)
Find all integers n for which (n^2+n+1)/(n-1) is an... (answered by josgarithmetic)
List all elements of the set A ∩ B, where A = {n ∈ N | n = 2^n − 1} and (answered by richard1234)
(n+1)! /... (answered by swincher4391)
solve for n... (answered by Fombitz)
{{{2^n -... (answered by ichudov)