12 50B C      B5− = = − . SUY RA ( )

13. - DAP AN DE THI THU KHOI A LAN 2 CHUYEN LAM SON
Toán DAP AN DE THI THU KHOI A LAN 2 CHUYEN LAM SON
13. 12 50b c      b5− = = − . Suy ra ( ) : 5P x−13y−12z−70=0.c c b