Question 3225
 (e^t - e^-t )/ 3 =2
 Let u = e^t, we have e^-t = 1/u,
 so (u - 1/u)/3 = 2, 
 Cancelling the denominator by multiply 3u,
 u^2 - 1 = 6u or 
 u^2 -6u - 1 = 0,
 By quadratic formula
 u = 3 + sqrt(10) or  3 - sqrt(10)(negative ,invalid)
 
 Since u = e^t = 3 + sqrt(10), so t = ln [3 + sqrt(10)]...Answer

 Check, t = ln 3, e^t =  3 + sqrt(10),
 e^t =  -3 + sqrt(10) 
 (e^t - e^-t )/ 3 = (3 - (-3))/3 = 2..correct

 Kenny