# Question on writing summations in expanded form

by mr_coffee
Tags: expanded, form, summations, writing
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 P: 1,629 Hello everyone. I have the following: THe sumnation of 1/k! from k = 0, to n. I"m suppose to write this in expanded form. I did the following: 1/0! + 1/1! + 1/2! + 1/3! +....+1/n! = 1 + 1 + 1/2 + 1/6 + 1/24 + 1/120 +...+ 1/n! Is that what they wanted? An example simliar to this one was the following: Sumnation (-2)^i from i = 1 to n. (-2)^1 + (-2)^2 + (-2)^3 + ... + (-2)^n = -2 + 2^2 -2^3 +...+(-1)^n(2)^n from mine the signs don't seem to be changing, so is it just simply 1/n! Also i was wondering if someone could check to see if i did this one correctly: Write each using summnation or product notation. 41. n + (n-1)/2! + (n-2)/3! + (n-3)/4! + .. + 1/n! I said: Sumnation from k = 1 to n, (n-k)/n! Thanks!
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P: 39,556
 Quote by mr_coffee Hello everyone. I have the following: THe sumnation of 1/k! from k = 0, to n. I"m suppose to write this in expanded form. I did the following: 1/0! + 1/1! + 1/2! + 1/3! +....+1/n! = 1 + 1 + 1/2 + 1/6 + 1/24 + 1/120 +...+ 1/n! Is that what they wanted?
Yes, that is correct.

 An example simliar to this one was the following: Sumnation (-2)^i from i = 1 to n. (-2)^1 + (-2)^2 + (-2)^3 + ... + (-2)^n = -2 + 2^2 -2^3 +...+(-1)^n(2)^n from mine the signs don't seem to be changing, so is it just simply 1/n! Also i was wondering if someone could check to see if i did this one correctly: Write each using summnation or product notation. 41. n + (n-1)/2! + (n-2)/3! + (n-3)/4! + .. + 1/n! I said: Sumnation from k = 1 to n, (n-k)/n! Thanks!
Not quite. n is a fixed number, k is changing so the denominator is not n!, it is k!.
 P: 1,629 Thanks for the help!

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