(8x2y-12x4y2)÷(-4xy)=________.
(a5b6-a3b2)÷ab=________;
3a2b2c÷(-a2b2)=________;
a2bx3÷a2x=_________;
判断题(对的打“∨”,错的打“×”)
(1)-4ab2÷2ab=2b;( ) (2)12a2b3c÷6ab2=2ab;( )
(3)4a5b4÷2a3b=2a2b3;( ) (4)6a7b8÷2a3b4·3a4b4=4a7b8÷6a7b8=1.( )
(a≠0)成立吗?说明理由.