We introduce and investigate two new types of fuzzy solutions to the equation f(a,x)=b where the parameters a and b are described in a fuzzy way. The solutions we propose are based on some known solutions to this type of equation with the parameters described by the interval data. We adapt to the fuzzy case so-called formal interval solutions (based on the Kaucher interval arithmetic) and AE-solution sets. In order to define fuzzy formal solutions we introduce a definition of fuzzy Kaucher arithmetic. We investigate the regularity of solutions in the case of linear dependence of f on a and discuss also the problem of interpretation and logical description of formal solutions.