posted by Courtney on .
11,406.14=(438.3/r)(1+r)^10 how do you solve for r?
These are very "nasty" equations, since there is no simple-level method of solving these.
I reduced it to
(1+r)^10 = 26.02359r
If you know Calculus, you can use Newton's Method,
otherwise, try something like this
It looks like your equation could have come from the amount of an annuity formula, so the r is probably an interest rate
make a chart with 3 columns
r | Left Side|Rigth Side
.05 1.62889 1.3 ---- off quite a bit
.06 1.79084 1.5614 --- let's go higher
.09 2.36736 2.345 --- hey, not bad
.095 2.4782 2.47224 -- closer !!
.096 2.50095 2.49826
.097 2.523866 2.524288 notice the Right side is now > the left side
so our r must be between .096 and .097
Do you get the idea?
With a good calculator and some calculator skills this is not so bad
BTW, I put 26.02359 into memory of calculator