先化简,再求值:[(xy+2)(xy-2)-2(x2y2-2)]÷(xy),其中x=10,y=-125.-数学

题目简介

先化简,再求值:[(xy+2)(xy-2)-2(x2y2-2)]÷(xy),其中x=10,y=-125.-数学

题目详情

先化简,再求值:[(xy+2)(xy-2)-2(x2y2-2)]÷(xy),其中x=10,y=-
1
25
题型:解答题难度:中档来源:荆州

答案

[(xy+2)(xy-2)-2(x2y2-2)]÷(xy),
=[(xy)2-22-2x2y2+4]÷(xy),
=(x2y2-4-2x2y2+4)÷(xy),
=(-x2y2)÷(xy),
=-xy,
当x=10,y=-class="stub"1
25
时,原式=-10×(-class="stub"1
25
)=class="stub"2
5

更多内容推荐