(* Created with the Wolfram Language for Students - Personal Use Only : www.wolfram.com *)
-(sP34*(2*CF*s34*(sP3*(-1 + z3) + sP4*z3)^2 + 
    CA*sP3*sP4*(sP3 - sP3*z3 + (sP4 - 2*s34*(-1 + z3))*z3)))/
 (2*s34*sP3^2*sP4^2*(-1 + z34)^2)
