On 12?23?, ??2?10?, "Roger Stafford" <ellieandrogerxy...@mindspring.com.invalid> wrote: > oversky <mail...@gmail.com> wrote in message <273d2ac5-844d-4b65-9833-5f1a98178...@37g2000prc.googlegroups.com>... > > >> solve('1/f = (n-1)(1/R1-1/R2-n/(n-1)*t/R1/R2)','t') > > - - - - - - - - > Apparently you have omitted the '*' multiplication operator following the first 'n-1' in your expression. That makes the expression invalid. Otherwise it should be easily solvable. > > Roger Stafford Thanks. I first tested this equation with f, and it went without problem. Then, I changed f to t. That's why I assumed the equation was input correctly.