Develop an expression of the work required to stretch

Question

F(x) =((k_BT)/(l_p))((1/4)(1-(x/L)^-2 +(x/L)-(1/4))

This is an example of a worm-like-chain (WLC) model, where l_p is persistence length and L is the contour length and k_B is Boltzmann's constant. Develop an expression of the work required to stretch a WLC fromx₁ to x₂.