问题
解答题
计算:
(1)6a5b6c4÷(-3a2b3c)÷(2a3b3c3).
(2)(x-4y)(2x+3y)-(x+2y)(x-y).
(3)[(-2x2y)2]3•3xy4.
(4)(m-n)(m+n)+(m+n)2-2m2.
答案
(1)原式=-2a3b3c3÷(2a3b3c3)=-1;
(2)原式=2x2-5xy-12y2-x2-xy+2y2=x2-6xy-10y2;
(3)原式=64x12y6•3xy4=192x13y10;
(4)原式=m2-n2+m2+2mn+n2-2m2=2mn.