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已知x+4y=-1.xy=5,求(6xy+7y)+【(8x-(5xy-y+6x)】
老师的格式为
∵x+4y=-1,xy=5
∴x= y=
(原式)
=xxxxxxxxxxxx
=xxxxxxxxxxxx
=xxxxxxxxxxxx(合并同类项 化简)
=xxxxxxxxxxxx(带入x与y的值)
=xxxxxxxxxx(最后结果)
人气:333 ℃ 时间:2020-03-31 18:02:57
解答
6xy+7y+[8x-5xy+y-6x]=6xy+7y+8x-5xy+y-6x=(6xy-5xy)+(7y+y)+(8x-6x)=xy+8y+2x=xy+2(4y+x)=5-2=3请问x=?y=? 上面格式你看到了∵x+4y=-1,xy=5 ∴x= y= (原式) =xxxxxxxxxxxx =xxxxxxxxxxxx =xxxxxxxxxxxx(合并同类项 化简)=xxxxxxxxxxxx(带入x与y的值) =xxxxxxxxxx(最后结果)x=-1-4y y=5/x 代入化简式中x乘以5/x+2(4y-1-4y)=5-2=3
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