View Full Version : Rearrange formulae
johnroba2
Jan 31, 2012, 07:26 AM
I need to rearrange the formula shown below
M = P*(1 IR)to the power N
I need it expressed in terms of IR
Thank you for your help
John Roberts
ebaines
Jan 31, 2012, 07:33 AM
I assume you mean this:
M=P(1+IR)^N
You can divide through by P:
\frac M P = (1 + IR)^N
Then take the nth root of both sides:
(\frac M P )^{(1/N)} = 1 + IR
Then subtract 1 from both sides:
(\frac M P )^{(1/N)} -1 = IR
johnroba2
Jan 31, 2012, 08:40 AM
Wow!Thanks very much for your help.
However Ive realised that the orinal equation was wrong
It should have been
M = P*(1+IR)+ (P*(1+IR))to the power N
to be expressed in terms of IR
Thanks again for your help
ebaines
Jan 31, 2012, 08:54 AM
M = P(1+IR) + (P(1+IR))^n
If you replace P(1+IR) with a, you have:
M = a + a^n
Unfortunately there is no closed form solution to express a in terms of M and n. If n = 2 you can use the quadratic equation to solve for a. But other than that case - you're limited to using numerical techniques to estimate a. Once you have that estimate then IR=(a/P)-1