计算:(1)(x2y)3·(﹣3x2y)·(xy2)2(2)(m2﹣mn+n2)(m2+mn+n2)(3)[(xy+2)(xy﹣2)﹣2x2y2+4]÷(xy)(4)(+1)2·(﹣+1)-七年级数学

题目简介

计算:(1)(x2y)3·(﹣3x2y)·(xy2)2(2)(m2﹣mn+n2)(m2+mn+n2)(3)[(xy+2)(xy﹣2)﹣2x2y2+4]÷(xy)(4)(+1)2·(﹣+1)-七年级数学

题目详情

计算:
(1)(x2y)3·(﹣3x2y)·(xy22
(2)(m2﹣mn+n2)(m2+mn+n2
(3)[(xy+2)(xy﹣2)﹣2x2y2+4]÷(xy)
(4)(+1)2·(+1)
题型:计算题难度:中档来源:重庆市期中题

答案

解:(1)(x2y)3·(﹣3x2y)·(xy2)2,
=x6y3(﹣3x2y)x2y4,
=﹣3x10y8;
(2)(m2﹣mn+n2)(m2+mn+n2),
=[(m2+n2)﹣mn][(m2+n2)+mn],
=(m2+n2)2﹣(mn)2,
=m4+m2n2+n4;
(3)[(xy+2)(xy﹣2)﹣2x2y2+4]÷(xy),
=(x2y2﹣4﹣2x2y2+4)÷(xy),
=﹣xy;
(4)原式=(+1)2·(﹣1)2,
=[()2﹣1]2,
=(﹣1)2,
=+1.

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