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已知x+y=5,xy=6,x+2分之1+y+2分之1=?
人气:256 ℃ 时间:2020-04-03 02:28:32
解答
1/(x+2)+1/(y+2)
=(x+2+y+2)/(x+2)(y+2)
=(x+y+4)/(xy+x+y+4)
=(5+4)/(6+5+4)
=3/5
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