... =)6(5467+−+−xxxxx=)6(54).6(.)6()6(7+−+−++xxxxxxxxx =)6(54)6(7 2 +−−+xxxx = )6(54 427 2 +−−+xxxx =)6( 127 2 +−−xxxxBài tập vận dụng 3 2 2 2 2 2 2 2 20x 4x 38 4 3 4 2 5 7 11, : ; , ; ,3 5 2 17 1 2 17 1 6 12 8 x x x xa b cy ... + 2 2 2 2 3 2 3 2 3 2 1 2 2 1, ; , ; , 2 1 2 4 6 9 9 1 1 1x x x xd e fx x x x x x x x x x− − ++ + + +− − + + − − + + −g) 3 2 7 4 2 2x xxy xy− −− ; i) 2 2 2 2 2 xy xx y ... (x-1)(x3+x 2 +x+1); 2/ (2x+1) 2 +2( 4x 2 -1)+(2x-1) 2 3/ (x 2 +xy+y 2 )(x-y) + (x 2 -xy+y 2 )(x+y); 4/ (x – 3)(x + 3) – (x – 3) 2 5/ ( x – 1 ) ( x + 1 ) – ( x – 1) 2 ; 6/ (x 2 –1)(x +2) – (x 2) (x 2 +2x+4)VD2:...