Here's my 2 cents. If the first two power terms use k, the 3rd power term
uses -A, and the 4th, 5th, and above use +A, then it appears to me that the
equation may be something like this...

A = (k*r*(1 + r)^(1 + n)*(2 + r))/((1 + r)^3 + (1 + r)^n*(-1 + r*(2 + r)*(1
+ r + r^2)))

With k = -1000, r=.0083333, and n=5, I get
-40555.08210206875
If your only approximate number 'r' of .0083333 is really .008333333333333,
(or more exactly 1/120), then I get your solution of -40554.92209880997

HTH
--
Dana DeLouis
Using Windows XP & Office XP
= = = = = = = = = = = = = = = = =


"Karl Thompson" wrote in message
...
Thank you.

A with your numbers is -506.206107674368

I agree, except for one thing. Sometimes A is negated, and sometimes it
isn't.

I see if I modify your divisor to this (2 neg signs removed) then the
result
is the expected
-40554.92:

1 - ( (-1*(1+R)^-3) + (1*(1+R)^-4) + (1*(1+R)^-5) )


This is great. Thanks.

Now to write the VBA code to do this....

"Tom Ogilvy" wrote in message
...
A = (K*(1+R)^-1) + (K*(1+R)^-2) + (-A*(1+R)^-3) + ... + (-A*(1+R)^-N)


A = (K*(1+R)^-1) + (K*(1+R)^-2) + A*((-1*(1+R)^-3) + ... +
(-1*(1+R)^-N))

A - A*((-1*(1+R)^-3) + ... + (-1*(1+R)^-N)) = (K*(1+R)^-1) +
(K*(1+R)^-2)

A * ( 1 - ((-1*(1+R)^-3) + ... + (-1*(1+R)^-N))) = (K*(1+R)^-1) +
(K*(1+R)^-2)

A = ((K*(1+R)^-1) + (K*(1+R)^-2)) / ( 1 - ((-1*(1+R)^-3) + ... +
(-1*(1+R)^-N)))

The answer for A with your numbers is -506.206107674368, checked by
substituting back in the original. So if you know the answer is
something
else, then the formula must not be given correctly.

--
Regards,
Tom Ogilvy

"Karl Thompson" wrote in message
...
Oh, sorry.

There is only one occurance of -A.

My assumption is though, that once I see how the equation is
rewritten,
that
I'll be able to figure out how make the necessary modifications myself
for
1) different values of N and 2) occassions when there may be more than
one
occurance of -A.



"Tom Ogilvy" wrote in message
...
(-A*(1+R)^-3) + ... + (A*(1+R)^-N)

at what point in the above sequence does -A become +A

--
Regards,
Tom Ogilvy

"Karl Thompson" wrote in message
...
Once again, I need a general equation that will solve for "A".
Can
someone
tell me what that would be please?


K = -1000
R = 0.0083333
N=5

A = (K*(1+R)^-1) + (K*(1+R)^-2) + (-A*(1+R)^-3) + ... +
(A*(1+R)^-N)

FYI: In this case I know A equals -40,554.920

Please note (don't know if it's important) that "A" can be negated
one
or
more times..

TIA