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rongbo_1025 幼苗
共回答了47个问题 举报
我觉得你题抄错了，第二个中括号里应该是x-y，不是x+y吧
[x+y-4xy÷(x+y)]×[x-y+4xy÷(x-y)]
=[(x+y)^2÷(x+y)-4xy÷(x+y)]×[(x-y)^2÷(x-y)+4xy÷(x-y)]
=[(x^2+2xy+y^2-4xy)÷(x+y)]×[(x^2-2xy+y^2+4xy)÷(x-y)]
=[(x-y)^2÷(x+y)]×[(x+y)^2÷(x-y)]
=(x-y)(x+y)
=x^2-y^2
[x+y-4xy÷(x+y)]×[x-y+4xy÷(x-y)]
=[(x+y)^2÷(x+y)-4xy÷(x+y)]×[(x-y)^2÷(x-y)+4xy÷(x-y)]
=[(x^2+2xy+y^2-4xy)÷(x+y)]×[(x^2-2xy+y^2+4xy)÷(x-y)]
=[(x-y)^2÷(x+y)]×[(x+y)^2÷(x-y)]
=(x-y)(x+y)
=x^2-y^2
1年前
0
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你能帮帮他们吗