Question

Find the indicated sum:
http://www.mathway.com/math_image.aspx?p=SMB02ASMB03sum,iSMB010,4SMB02aSMB03(-1)SMB02ESMB03i+1SMB02eSMB03i!?p=98?p=48

Answer 1

is that i! (i factorial) written there?

Answer 2

yes

Answer 3

hmm..so where are you stuck ?

Answer 4

I keep getting 45, but my teacher says it's 28

Answer 5

can i see your work ?

Answer 6

Sure- wait

Answer 7

s4= 1(1-4!)/1-4!

Answer 8

it's actually 47 sorry

Answer 9

i was using the sum formula

Answer 10

o.O

which formula is this?
anyways, why would you need a formulla? just keep on putting values of i from 0 to 4 and add each term..ans would be
(-1)^(0+1)* 0! + (-1)^(1+1)* 1! + (-1)^(2+1)* 2! + ..... till i=4..

did you follow ?

Answer 11

wait a sec

Answer 12

i need to use the formula to get credit on my test, this is it https://www.softchalkcloud.com/lesson/files/JWSnYa7QyqLGc8/Geometric%20Sequence%20Sum%20Formula.jpg

Answer 13

yours is not a geometric series! this is the formula for sum of geometric series..

Answer 14

so i should be using an artithmatic one?

Answer 15

there is no formulla involved..you'll have to plug in values i one by one and find the sum..