Question on setting up excell to solve a math problem

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frank c - 27 Oct 2006 20:06 GMT

Is there a way to solve Y=((1+x)^5)/x with Y known in excell? There is no
way to solve this algabraically that I am aware of.

Thank You,
Frank

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David Biddulph - 27 Oct 2006 20:21 GMT

Tools/ Goal Seek.

Signature

David Biddulph

> Is there a way to solve Y=((1+x)^5)/x with Y known in excell? There is no
> way to solve this algabraically that I am aware of.
>
> Thank You,
> Frank

Reply to this Message

Ron Coderre - 27 Oct 2006 20:22 GMT

Maybe using Goal Seek?:

With
B1: 1
A1: =((1+B1)^5)/B1
(Note: at that point A1 returns 32

Fom the Excel main menu:
<tools><goal seek>
Set cell: A1
To value: 1555.2
By changing cell: B1
Click [OK]

Goal Seek returns a solution of: 5

Does that help?
***********
Regards,
Ron

XL2002, WinXP

> Is there a way to solve Y=((1+x)^5)/x with Y known in excell? There is no
> way to solve this algabraically that I am aware of.
>
> Thank You,
> Frank

Reply to this Message

Dana DeLouis - 30 Oct 2006 04:30 GMT

Another option might be the Newton equation. Taking Ron's excellent
example, we can find the other two real solutions.

'// Given y, solve for x with an initial guess for x.

Function MyFx(y, x)
Dim j
For j = 1 To 20
x = (x * ((3 * x - 2) * (x + 1) ^ 4 + x * y)) / ((x + 1) ^ 4 * (4 * x -
1))
Next j
MyFx = x
End Function

Sub TestIt()
Debug.Print MyFx(1555.2, -5)
Debug.Print MyFx(1555.2, 0.0001)
Debug.Print MyFx(1555.2, 5)
End Sub

Returns the 3 Real solutions:
-7.50826391236509
6.45080740534675E-04
5

Signature

HTH :>)
Dana DeLouis
Windows XP & Office 2003

> Maybe using Goal Seek?:
>
[quoted text clipped - 25 lines]
>> Thank You,
>> Frank

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