12(x+y)平方+11(x方-y方)+2(x-y)平方=

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12(x+y)平方+11(x方-y方)+2(x-y)平方=

12(x+y)平方+11(x方-y方)+2(x-y)平方=
12(x+y)平方+11(x方-y方)+2(x-y)平方=

12(x+y)平方+11(x方-y方)+2(x-y)平方=
12(x+y)²+11(x²-y²)+2(x-y)²
=12(x+y)²+11(x+y)(x-y)+2(x-y)²
=[3(x+y)+2(x-y)][4(x+y)+(x-y)]
=(3x+3y+2x-2y)(4x+4y+x-y)
=(5x+y)(5x+3y)

原式=12(x^2+2xy+y^2)+11*(x^2-y^2)+2*(x^2-2xy+y^2)
=(12+11+2)x^2+(24-4)*xy+(12-11+2)y^2
=25x^2+20xy+3y^2