.  MỘT SỐ BI TON CC TR TRONG HNH HC GII TCH LP 12   . Y& a(B"8#-%.!9  :9 : 9 # :(;%#<=>  :>  ::> # 2"?>  @>  @A@> # B >CD(E-FG#*2"4#*H"I !12 3"4#*567 !-%.!2J0#-FG#*2"4#*H "I !12 3"4#*567<8$"8      ***       . T%UVSU WCXY:ZS[    !" #"$"%&'(')#**+$$,-%.!/0# !12 3"4#*567 −M-#"<8/+ hbid* −j#     