What do you mean by "equations"? Your uAl,uC are two expressions, not equations, and they contain three variables. What do you want to do with them?
Use Rationalize to convert Real to exact Rational. e.g.
Rationalize
Real
Rational
Rationalize[uAl, 0]
Thank you for your reply. But uAl= 0, I don't see how rationalize would solve the problem.
.