Bai_01_Phuong_phap_ham_so Bai_02_Tinh_don_dieu_cua_hs_20.04_ Bai_03_GTLN_NN_cua_hs Bai_04 Bai_9_BTTL_PP_su_dung_bdt_Bunhiacopxkii Bai_9_HDGBTTL_PP_su_dung_bdt_Bunhiacopxkii Bai_9_TLBG_PP_su_dung_bdt_Bunhiacopxkii Bai_10_BTTL_Su_dung_bdt_cho_truoc_tim_GTLN_GTNN