TeX source:

=hm[∫^{TR}_{0}p_mtdt+∑^{1}_{r−1}∫^{(i+1)T_R}_{iT_R}(p_mt−iD_R)dt+∫^{(T_s}_{rT_R}(p_mt−rD_R)dt \\ + ∫^{(r+1)T_R}_{T_s}(p_mT_s−rD_R)dt+∑_{r+1}^{n−1}∫^{(i+1)T_R}_{iT_R} (p_mT_s−iD_R)dt+∫^{(n+1)T_R}_{nT_R} (p_mT_s−nD_R)dt] \\ =h_m[np_mT_sT_R−\dfrac{n^2+n−2r−2}{2}T_RD_R−\dfrac{p^{2}_{s}t^{2}_{s}}{2p_m}]