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