1.(3m-2n)三次方+(3m+2n)三次方 2.x六次方（x方-y方）+y六次方（y方-x方） 3.8（x+y）3+
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1.(3m-2n)三次方+(3m+2n)三次方
=(3m-2n+3m+2n)[(3m-2n)^2-(3m-2n)(3m+2n)+(3m+2n)^2]
=6m[9m^2-12mn+4n^2-9m^2+4n^2+9m^2+12mn+4n^2]
=6m(9m^2+12n^2)
=18m(3m^2+4n^2)
2.x六次方（x方-y方）+y六次方（y方-x方）
=x^6(x^2-y^2)-y^6(x^2-y^2)
=(x^6-y^6)(x^2-y^2)
=(x^2-y^2)(x^4+x^2y^2+y^4)(x^2-y^2)
=(x^2-y^2)^2(x^4+x^2y^2+y^4)
=(x+y)^2(x-y)^2(x^4+x^2y^2+y^4)
3.8（x+y)^3+1
=(2(x+y)+1)[(2(x+y))^2-2(x+y)+1]
=(2x+2y+1)(2x^2+4xy+2y^2-2x-2y+1)
4.（a+b+c）三次方-a三次方-b三次方-c三次方
=（a+b+c）^3-a^3-(b^3+c^3)
=（a+b+c-a）[ (a+b+c)^2+a(a+b+c)+a^2]-(b+c)(b^2-bc+c^2)
=（b+c）[ a^2+b^2+c^2+2ab+2bc+2ac+a^2+ab+ac+a^2]-(b+c)(b^2-bc+c^2)
=（b+c）(3a^2+b^2+c^2+2ab+2bc+2ac+ab+ac-b^2+bc-c^2)
=（b+c）(3a^2+3ab+3bc+3ac)
=3（b+c）(a^2+ab+bc+ac)
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