(1)原式=x 16•x 4÷x 10-2x 5•x 6÷x=x 10-2x 10=-x 10;
(2)原式=3ab 2+a 2b 2-3ab 2-5a 2b 2=-4a 2b 2;
(3)原式=x 2-9-x 2-4x-3=-4x-12;
(4)原式=4x 2-y 2+x 2+2xy+y 2-4x 2+2xy=x 2+4xy.
(1)原式=x 16•x 4÷x 10-2x 5•x 6÷x=x 10-2x 10=-x 10;
(2)原式=3ab 2+a 2b 2-3ab 2-5a 2b 2=-4a 2b 2;
(3)原式=x 2-9-x 2-4x-3=-4x-12;
(4)原式=4x 2-y 2+x 2+2xy+y 2-4x 2+2xy=x 2+4xy.