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What is the Sum of 1^3+2^3+3^3+4^3+5^3+6^3+7^3 [#permalink]
27 Jul 2013, 13:14

What is the sum of series S? Is there a shortcut/formula? I understand you can evaluate and sum each expression but I am trying to find a better solution.

Re: What is the Sum of 1^3+2^3+3^3+4^3+5^3+6^3+7^3 [#permalink]
27 Jul 2013, 13:20

1

This post received KUDOS

alphabeta1234 wrote:

What is the sum of series S? Is there a shortcut/formula? I understand you can evaluate and sum each expression but I am trying to find a better solution.

S=1^3+2^3+3^3+4^3+5^3+6^3+7^3

Is there a general formula for S(k,a)=Sum(a^k)?

Hi,

i think there will be no need of these types of formulas in GMAT,BUT STILL HERE IT IS:

Re: What is the Sum of 1^3+2^3+3^3+4^3+5^3+6^3+7^3 [#permalink]
29 Jul 2013, 03:58

blueseas wrote:

alphabeta1234 wrote:

What is the sum of series S? Is there a shortcut/formula? I understand you can evaluate and sum each expression but I am trying to find a better solution.

S=1^3+2^3+3^3+4^3+5^3+6^3+7^3

Is there a general formula for S(k,a)=Sum(a^k)?

Hi,

i think there will be no need of these types of formulas in GMAT,BUT STILL HERE IT IS:

Re: What is the Sum of 1^3+2^3+3^3+4^3+5^3+6^3+7^3 [#permalink]
29 Jul 2013, 06:45

1

This post received KUDOS

sophietrophy wrote:

blueseas wrote:

alphabeta1234 wrote:

What is the sum of series S? Is there a shortcut/formula? I understand you can evaluate and sum each expression but I am trying to find a better solution.

S=1^3+2^3+3^3+4^3+5^3+6^3+7^3

Is there a general formula for S(k,a)=Sum(a^k)?

Hi,

i think there will be no need of these types of formulas in GMAT,BUT STILL HERE IT IS:

Re: What is the Sum of 1^3+2^3+3^3+4^3+5^3+6^3+7^3 [#permalink]
29 Jul 2013, 23:13

1

This post received KUDOS

Expert's post

alphabeta1234 wrote:

What is the sum of series S? Is there a shortcut/formula? I understand you can evaluate and sum each expression but I am trying to find a better solution.

S=1^3+2^3+3^3+4^3+5^3+6^3+7^3

Is there a general formula for S(k,a)=Sum(a^k)?

You can solve it using pattern recognition. If you know the formula, it does save you time but then, there are many many formulas and you certainly cannot memorize all of them. So you should be comfortable with some such basic techniques. I have discussed how to use pattern recognition for this question here: http://www.veritasprep.com/blog/2013/01 ... n-part-ii/ _________________