TeX source:

=\dfrac{1}{T}[(c_r−c_m)p_mT_h_m(np_mT_sT_R−\dfrac{n^2+n−2r−2}{2}T_RD_R−\dfrac{p^{2}_{s}t^{2}_{s}}{2pm}) \\ −id)m(\dfrac{p_mT_m−nD_R}{D_c})+\dfrac{nc_rI_p}{2}[T_RD_R+D_cM^2−2MD_R] \\ +c_rI_p(\dfrac{(p_mT_s−nD_R)^2}{2D_c}+(p_mT_s−nD_R)M+\dfrac{D_cM^2}{2})−Am]