(x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一

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(x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一

(x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一
(x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一

(x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一
(x+y)(x-y)+(x-y)平方-(x-y)(3x-y)
=(x-y)(x+y+x-y-3x+y)
=(x-y)(-x+y)
=-(x-y)²
=-(-2-3分之一)²
=-(-3分之7)²
=-9分之49

(x^2-y^2)+x^2+y^2-2xy-(3x^2-4xy+y^2)
=-x^2-y^2+2xy
=-(x-y)^2
=-(-5)^2=-25

(x+y)(x-y)+(x-y)²-(x-y)(3x-y)
=(x-y)(x+y+x-y-3x+y)
=-(x-y)²
当x=-2 y=1/3时,原始=-(-2-1/3)²=-49/9

-25