(* Created with the Wolfram Language for Students - Personal Use Only : www.wolfram.com *)
(2*CF*s34^2*z34*z4 - CA*z4*(s34^2*z4 + s34*sP3*z4 + s34*sP4*(-2*z3 + z4) + 
    2*sP4*(-(sP4*z3) + sP3*z4)))/(2*s34^2*sP4*(-1 + z34)*z34)
