...BÀI 8: 1, x + x + x − x +1 2, ( x + y + z )( x + y + z ) + ( xy + yz + zx) 1, x + x + 2, x + x5 + 3, x5 + x + 4, x + x + 5, x8 + x + 6, x − x − 7, x5 +