Find the sum, using the formulas for the sums of the powers of integers.

11

∑(-2-n^3+2n)

n=1

Printable View

- Oct 5th 2009, 08:54 PMflexusPower of intergers
Find the sum, using the formulas for the sums of the powers of integers.

11

∑(-2-n^3+2n)

n=1 - Oct 5th 2009, 08:57 PMChris L T521
- Oct 5th 2009, 09:05 PMthepride
- Oct 5th 2009, 09:10 PMflexus
i dont think that is the right answer the pride.. i see what you did though. you plugged 11 into n. you used the second equation. thanks for helping. the answer is will not help me if i don't understand this. can someone confirm his answer with a little explanation?

- Oct 5th 2009, 09:14 PMChris L T521
- Oct 5th 2009, 09:24 PMflexus
- Oct 5th 2009, 09:26 PMChris L T521
- Oct 5th 2009, 09:31 PMflexus
- Oct 5th 2009, 09:39 PMChris L T521
- Oct 5th 2009, 09:47 PMflexus
omg i wrote the problem wrong. ok let me do this over.

the correct problem is:

15

∑(-2-n^3+2n)

n=1

ok so now i plug that into the three equations.

(-2)(15)-(15(15+1))/2+15(15+1)^2)/2 the i get:

-30-240/2+1920 which equals =1770 but this does not match the answer in my book. i must have done something wrong? can you confirm please? - Oct 5th 2009, 09:50 PMChris L T521
- Oct 5th 2009, 09:56 PMflexus
- Oct 5th 2009, 09:58 PMChris L T521
- Oct 5th 2009, 10:04 PMflexus
- Oct 5th 2009, 10:41 PMChris L T521