化简求值:[(x+2y)2-(x+y)(3x-y)-5y2]÷2x,其中x=-2,y=1/2.
化简求值:[(x+2y)
2-(x+y)(3x-y)-5y
2]÷2x,其中x=-2,y=
.
数学人气:157 ℃时间:2019-08-17 14:29:34
优质解答
[(x+2y)
2-(x+y)(3x-y)-5y
2]÷2x
=(x
2+4xy+4y
2-3x
2-2xy+y
2-5y
2)÷2x
=(-2x
2+2xy)÷2x
=y-x,
当x=-2,y=
时,
原式=
-(-2)=
.
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