@C_R So you mean change this
indets(eqn) minus indets(eqn,name);
subexpr:=map(op,%) minus indets(%,fraction):# remove of root terms - instead of filtering for `^`
indets(eqn,`^`) gives, which has the a^2 ...e^2
{a^2, b^2, c^2, d^2, e^2, 1/(a*c - b^2/4), 1/(4*a*c - b^2)^2, (4*a*c*f - a*e^2 - b^2*f + b*d*e - c*d^2)^2, sqrt((a^2 - 2*a*c + b^2 + c^2)*(4*a*c*f - a*e^2 - b^2*f + b*d*e - c*d^2)^2), sqrt(2*sqrt((a^2 - 2*a*c + b^2 + c^2)*(4*a*c*f - a*e^2 - b^2*f + b*d*e - c*d^2)^2) + (-8*a*f + 2*d^2)*c^2 + (8*a^2*f - 2*a*d^2 + 2*a*e^2 + 2*b^2*f - 2*b*d*e)*c - 2*a^2*e^2 - 2*a*b^2*f + 2*a*b*d*e), sqrt(2*sqrt((a^2 - 2*a*c + b^2 + c^2)*(4*a*c*f - a*e^2 - b^2*f + b*d*e - c*d^2)^2) + (8*a*f - 2*d^2)*c^2 + (-8*a^2*f + 2*a*d^2 - 2*a*e^2 - 2*b^2*f + 2*b*d*e)*c + 2*a^2*e^2 + 2*a*b^2*f - 2*a*b*d*e)}