1. The problem statement, all variables and given/known data How do I express t and s as functions of x and y given x = -(2t+1)*s/(t^2-1) y = e^(t + ln|s|) I keep getting stuck in a loop. 2. Relevant equations substitution 3. The attempt at a solution x= -(2t+1)*s/(t^2-1) I get t = sqrt(1-s/x) t = sqrt(1-s/x) s = e^(-t)y substituting the terms in either expression gets me stuck in a loop. What am I doing wrong? what I need is t = T(x,y) and s = S(x,y). The other important part is that s needs to stay any real number. Thanks!