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