①(z减y)(y减x)(x减z)分之(x减y)(y减z)(z减x)②x平方减y平方分之y减x这些怎么化简还有个m²减4n²分之m+2n怎么约分,约分后求值m=1,n=3

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①(z减y)(y减x)(x减z)分之(x减y)(y减z)(z减x)②x平方减y平方分之y减x这些怎么化简还有个m²减4n²分之m+2n怎么约分,约分后求值m=1,n=3
①(z减y)(y减x)(x减z)分之(x减y)(y减z)(z减x)②x平方减y平方分之y减x这些怎么化简
还有个m²减4n²分之m+2n怎么约分,约分后求值m=1,n=3

①(z减y)(y减x)(x减z)分之(x减y)(y减z)(z减x)②x平方减y平方分之y减x这些怎么化简还有个m²减4n²分之m+2n怎么约分,约分后求值m=1,n=3
(x-y)(y-z)(z-x)/((z-y)(y-x)(x-z))=(x-y)(y-z)(z-x)/(-(y-z)(x-y)(z-x))=-1
(y-x)/(x²-y²)=-(x-y)/(x+y)(x-y)=-1/(x+y)
(m+2n)/(m²-4n²)=(m+2n)/((m+2n)(m-2n))=)1/(m-2n)
把m=1,n=3代入得:1/(1-2*3)=-1/5