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      08-06-2009, 07:38 PM   #1
sokdo
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Simple Math Equation shortcut help

I remember there was an easy way or a short cut method of figuring this out but I just can't remember, maybe some of you guys can remember back to your high school days?

So solve this equation:

(5/((x+1)^1)+(5/((x+1)^2)+(5/((x+1)^3).....+(5/((x+1)^60) = 50
find X


Wasn't there a shortcut method to solving this really easily? Its like on the tip of my tongue and it's driving me insane lol
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      08-06-2009, 07:41 PM   #2
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OH FUCK!
its also on the tip of my tounge, i have the notes somewhere around here...
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      08-06-2009, 07:43 PM   #3
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wtf is ...... ?
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      08-06-2009, 07:49 PM   #4
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Quote:
Originally Posted by Cyber View Post
wtf is ...... ?
It means you keep going until you eventually hit to the ^60 so

x^1....+x^6 means
X^1 + x^2 + x^3 + x^4 + x^5 + x^6
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      08-06-2009, 07:49 PM   #5
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lmao i hope this one's a joke
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      08-06-2009, 07:53 PM   #6
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Quote:
Originally Posted by jrsbeamer335 View Post
lmao i hope this one's a joke
Nope it sure aint =) By all means please enlighten me if you know how to solve it with the formula and without having to plug those numbers one by one into a calculator
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      08-06-2009, 08:38 PM   #7
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its a power series. You may want to look into this website:
http://appsci.queensu.ca/courses/APS...ments/nops.pdf

but to simple things out, here's a general equation that you can use c/(1-x)
where c is 5 in this case, and x is 1/(x+1) and something like that.

and that is as far as I remember from my calculus class...lol
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      08-06-2009, 08:52 PM   #8
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      08-06-2009, 09:22 PM   #9
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hehe are u studying for the GMAT?
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      08-07-2009, 12:35 AM   #10
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Quote:
Originally Posted by sokdo View Post
I remember there was an easy way or a short cut method of figuring this out but I just can't remember, maybe some of you guys can remember back to your high school days?

So solve this equation:

(5/((x+1)^1)+(5/((x+1)^2)+(5/((x+1)^3).....+(5/((x+1)^60) = 50
find X


Wasn't there a shortcut method to solving this really easily? Its like on the tip of my tongue and it's driving me insane lol
You might be thinking of the fact that in geometric series' (meaning the ratio between elements is constant) of the following type:


1 + 1/(n^1) + 1/(n^2) + 1/(n^3) ... 1/n^N = 1 / ( 1 - ( 1 / n))

i.e.

1 + 1/2 + 1/4 + 1/8 + 1/16 + ... = 1 / (1 - ( 1 / 2 )) = 2




I'm just taking a stab at what you're looking for/remembering. The series you posted terminates, so I'm not sure what you're looking for.
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      08-07-2009, 01:09 AM   #11
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Radix you got it haha thanks for all the replies. Actually nah it was something I came up while my friend's younger sis was doing her school work and it just seemed so familiar lol but I don't remember anything from high school too much football
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      08-07-2009, 01:50 AM   #12
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well there ya go, was going to give you a summation and a formula to figure it out, but I think radix got to it
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      08-07-2009, 02:00 AM   #13
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what is this? high school math?
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      08-07-2009, 02:02 AM   #14
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fuck math
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      08-07-2009, 02:02 AM   #15
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^ says the IT guy who got a closet as his new office

edit: you probably get paid more than math teachers, though.
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      08-07-2009, 02:06 AM   #16
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Quote:
Originally Posted by darkphantom View Post
edit: you probably get paid more than math teachers, though.
honestly, i'd work outside in this texas heat for what i'm getting paid. closet is great! it's also the coolest room in the building.
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      08-07-2009, 02:07 AM   #17
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no shit, it's the server room! plus, no one disturbs you but make you walk around every once in a while! don't want to become the caveman now...
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      08-07-2009, 02:33 AM   #18
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Quote:
Originally Posted by darkphantom View Post
no shit, it's the server room! plus, no one disturbs you but make you walk around every once in a while! don't want to become the caveman now...
i go make a fry's run around noon then proceed to take lunch. i take a lot of cigarette breaks, but i'm doing 5x what the old IT guy did. i've been working late because there are a lot of OE's during business hours, and i'm not a huge fan, but i don't like waking up early anyway.
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      08-07-2009, 02:34 AM   #19
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oh sorry for the
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      08-07-2009, 03:17 AM   #20
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i think its called mathematical induction. you replace the X with 1 then prove it, then replace x with k and prove it, then replace x with k+1 and prove it. if all the proofs work out then there you go.
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      08-07-2009, 03:20 AM   #21
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Quote:
Originally Posted by asian010 View Post
i think its called mathematical induction. you replace the X with 1 then prove it, then replace x with k and prove it, then replace x with k+1 and prove it. if all the proofs work out then there you go.
Mathematical induction is used to prove that a mathematical statement is true. What he wanted was a shortcut for the summation of a geometric series.
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      08-07-2009, 03:28 AM   #22
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Quote:
Originally Posted by radix View Post
Mathematical induction is used to prove that a mathematical statement is true. What he wanted was a shortcut for the summation of a geometric series.
ahh mybad just looked at the equation agian.

so i pulled out my notes and found this formula under geometric series

1x1-r^n / 1-r
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