HEllo,
Im just trying to remember the algebraic method of sloving for r in an equ. such as this.
a = (1 + (r/m) )^m - 1
$\displaystyle a = \left ( 1 + \frac{r}{m} \right )^m - 1$
$\displaystyle a + 1 = \left ( 1 + \frac{r}{m} \right )^m$
$\displaystyle 1 + \frac{r}{m} = (a + 1)^{1/m}$
$\displaystyle \frac{r}{m} = (a + 1)^{1/m} - 1$
$\displaystyle r = \frac{1}{m} \left ( (a + 1)^{1/m} - 1 \right )$
-Dan