## anonymous 5 years ago Summation Evaluate these summations. a) N(E)k=1 (k-k^3) b) N-1(E)k=1 (k^2/N^2) Note that (E) is the summation symbol. Not sure how to do these. Help would be appreciated

1. anonymous

hey m not sure i understand..r the terms on the right the expression for the kth term??

2. anonymous

do we have to evaluate the sum of the series whose term is k-k^3????clarify and i cn help

3. anonymous

sorry it's all squashed together, didn't notice! there are two questions: a) N (E) k=1 (k-k^3) b) N-1 (E) k=1 (k^2/N^2) where N = natural numbers and (E) is the summation symbol The N and N-1 for the questions are on top of the summation symbol and the k =1 are below the symbol. The (k-k^3) and (k^2/N^2) are on the right sides of the summation symbol.

4. anonymous

u can use the equation tab to write it in mathematical format

5. anonymous

ugghh it keeps squashing together - but a) and b) are separate questions

6. anonymous

N(N+1)/2 + [N(N+1)/2]^2

7. anonymous

thats a)

8. anonymous

as for b) (N-1)(N)(2N-1)/6N ^2

9. anonymous

$\sum_{k=1}^{N}(k-k^3)$

10. anonymous

yes uzma that's the correct format for a)

11. anonymous

and b?????

12. anonymous

$\sum_{k}^{N-1}(k^2/N^2)$

13. anonymous

14. anonymous

Yes that's the correct one for b) him1618, thanks for your help :) and uzma too :)

15. anonymous

no prob

16. anonymous

did u understand the solution?

17. anonymous

Yes, thank you :)

18. anonymous

welcome:)

19. anonymous

wht tym is it there at ur place?

20. anonymous

9:02pm

21. anonymous

where r u?

22. anonymous

new zealand

23. anonymous

k...

24. anonymous

N(E)K=1(K-K^3) (E)1/1-K^2=1/N N=1-K^2 K=1 N=0

25. anonymous

what sort of followup is this kihaga???

26. anonymous

Yes! that is Honorata kihaga