约分分式 (1)x-y/-x+y (2)(x+y)^2/2(x+y)^3 (3)2mn/2m^2+4mn (4)2(a-b)^2/a^2-b^2(5)x^2+6xy+9y^2/x^2-9y^2

问题描述:

约分分式 (1)x-y/-x+y (2)(x+y)^2/2(x+y)^3 (3)2mn/2m^2+4mn (4)2(a-b)^2/a^2-b^2
(5)x^2+6xy+9y^2/x^2-9y^2

(x-y)/(-x+y)=(x-y)/-(x-y)=-1(x+y)^2/2(x+y)^3=1/(2(x+y))2mn/2m^2+4mn=(n+4nm^2)/m,2mn/(2m^2+4mn)=n/(m+2n)2(a-b)^2/(a^2-b^2)=2(a-b)^2/((a-b)(a+b))=2(a-b)/(a+b)(x^2+6xy+9y^2)/(x^2-9y^2)=(x+3y)^2/((x-3y)(x...