三克油!\(≧▽≦)/~[(x+2y)^2-(x-2y)^2-(x+2y)(x-2y)-4y^2]÷2x,其中x=-2,y=1/2.

三克油!\(≧▽≦)/~[(x+2y)^2-(x-2y)^2-(x+2y)(x-2y)-4y^2]÷2x,其中x=-2,y=1/2.
三克油!\(≧▽≦)/~
[(x+2y)^2-(x-2y)^2-(x+2y)(x-2y)-4y^2]÷2x,其中x=-2,y=1/2.

三克油!\(≧▽≦)/~[(x+2y)^2-(x-2y)^2-(x+2y)(x-2y)-4y^2]÷2x,其中x=-2,y=1/2.
原式=(x^2+4y^2+4xy-x^2-4y^2+4xy-x^2+4y^2-4y^2)/2x
=8xy-x^2
=8*(-2)*1/2-(-2)^2
=-12

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xgfnjzxfgm

[(x+2y)^2-(x-2y)^2-(x+2y)(x-2y)-4y^2]÷2x
=[(x+2y-x+2y)(x+2y+x-2y)-(x^2-4y^2)-4y^2]÷2x
=[8xy-x^2]÷2x
=(8y-x)÷2
=(4+2)/2
=3

(x+2y)^2-(x-2y)^2-(x+2y)(x-2y)-4y^2＝[(x+2y)+(x-2y)]*[(x+2y)-(x-2y)]-(x^2-4y^2)-4y^2=8xy-x^2
原式＝(8xy-x^2)/2x=4y-x/2=4*1/2-(-2)/2=2+1=3

={[（x+2y)+(x-2y)][(x+2y)-(x-2y)]-(x^2-4y^2)-4y^2}/2x
={8xy-x^2}/2x
=4y-x/2=2+1=3大哥你式子都错了还3？？？！！！我没错，你不信问下你老师不就知道我是否是正确的
(x+2y)^2=a,(x-2y)^2=b
(x+2y)^2-(x-2y)^2
a^2-b^2=(a+b)(a-b)

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={[（x+2y)+(x-2y)][(x+2y)-(x-2y)]-(x^2-4y^2)-4y^2}/2x
={8xy-x^2}/2x
=4y-x/2=2+1=3

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[(x+2y)^2-(x-2y)^2-(x+2y)(x-2y)-4y^2]÷2x = [ x^2+4xy+4y^2-x^2+4xy-4y^2-（x^2-2xy+2xy-4y^2）-4...

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[(x+2y)^2-(x-2y)^2-(x+2y)(x-2y)-4y^2]÷2x = [ x^2+4xy+4y^2-x^2+4xy-4y^2-（x^2-2xy+2xy-4y^2）-4y^2 ]÷2x =（x^2+4xy+4y^2-x^2+4xy-4y^2-x^2+2xy-2xy+4y^2-4y^2） ÷2x =（-x^2+8xy）÷2x 原式= [ -(-2）^2+8X(-2）X1/2] ÷2X(-2）=（-4-8）÷（-4）=3

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