(x-y)的平方+(x+y)(x-y),其中x=1/3,y=1/6

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(x-y)的平方+(x+y)(x-y),其中x=1/3,y=1/6(x-y)的平方+(x+y)(x-y),其中x=1/3,y=1/6(x-y)的平方+(x+y)(x-y),其中x=1/3,y=1/6(

(x-y)的平方+(x+y)(x-y),其中x=1/3,y=1/6
(x-y)的平方+(x+y)(x-y),其中x=1/3,y=1/6

(x-y)的平方+(x+y)(x-y),其中x=1/3,y=1/6
(x-y)的平方+(x+y)(x-y),
=(x-y)(x-y)+(x+y)(x-y)
=(x-y)(x-y+x+y)
=2x(x-y)
=2x平方-2xy

x=1/3,y=1/6时
原式=2*(1/3)²-2*1/3*1/6
=2/9-2/3
=-4/9