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Mathematics 7 Online
OpenStudy (anonymous):

Calculus help?

OpenStudy (anonymous):

OpenStudy (anonymous):

@phi , @ranga @surjithayer ?

OpenStudy (ranga):

Are you supposed to prove the summation is 2970?

OpenStudy (anonymous):

I am supposed to solve it and I'm guessing it is 2970? but how do I solve it?

OpenStudy (ranga):

Are you given the formula for: i = 1 to n of sigma (i^3) ?

OpenStudy (anonymous):

there are some theorems

OpenStudy (anonymous):

i'll attach them

OpenStudy (anonymous):

OpenStudy (anonymous):

∑▒〖i(i^2-1)=∑▒i^3 - ∑▒i=(i^(2 ) (i+1)^2)/4〗-i(i+1)/2 Put i=10 and get the solution [ ∑▒n^3 =(∑▒n)^2 ∑▒n=n(n+1)/2 ]

OpenStudy (ranga):

The problem asks you to find the sum of: i = 1 to 10 of Sigma i * (i^2 - 1) Since we will make use of the theorems, let us do a general summation by using "n" in the place of 10: Find: { i = 1 to n of Sigma i * (i^2 - 1) } = { i = 1 to n of Sigma i^3 } - { i = 1 to n of Sigma i } substitute the formula from the theorems: = n^2(n+1)^2/4 - n(n+1)/2 Put n = 10 = 10^2 * (10 + 1)^2 / 4 - 10(10+1)/2 = 100 * 121 / 4 - 10 * 11 / 2 = 3025 - 55 = 2970

OpenStudy (anonymous):

Thank you so much. I get confused as to which theorem to use.

OpenStudy (anonymous):

Thanks again!

OpenStudy (ranga):

You are welcome.

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