(%i1) load(solve_rat_ineq)$ (%i2) ineq:(x^2-x-6)/(x^2-7*x+12)<0; (%o2) (x^2-x-6)/(x^2-7*x+12)<0 (%i3) solve_rat_ineq(ineq); (%o3) [[x>-2,x<4]] Is x=3 solution? (%i4) subst(x=3,ineq); expt: undefined: 0 to a negative exponent. -- an error. To debug this try: debugmode(true); Aleksas D