作业帮约分:(1)2m(m-n)/4m(n-m)^2 (2)2m(m-n)/4m(n-m) (3)m^2-4/2m+m^2 (4)a^2-4a+4/a^2-4 (5)x^2-4x+4/x^2-4约分:(1)2m(m-n)/4m(n-m)^2 (2)2m(m-n)/4m(n-m) (3)m^2-4/2m+m^2(4)a^2-4a+4/a^2-4 (5)x^2-4x+4/x^2-4 (6)a^2+4ab/a^2b+4ab^2(7)先化简,再求值（a^2-4)/(
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约分:(1)2m(m-n)/4m(n-m)^2 (2)2m(m-n)/4m(n-m) (3)m^2-4/2m+m^2 (4)a^2-4a+4/a^2-4 (5)x^2-4x+4/x^2-4约分:(1)2m(m-n)/4m(n-m)^2 (2)2m(m-n)/4m(n-m) (3)m^2-4/2m+m^2(4)a^2-4a+4/a^2-4 (5)x^2-4x+4/x^2-4 (6)a^2+4ab/a^2b+4ab^2(7)先化简,再求值（a^2-4)/(
约分:(1)2m(m-n)/4m(n-m)^2 (2)2m(m-n)/4m(n-m) (3)m^2-4/2m+m^2 (4)a^2-4a+4/a^2-4 (5)x^2-4x+4/x^2-4
约分:(1)2m(m-n)/4m(n-m)^2 (2)2m(m-n)/4m(n-m) (3)m^2-4/2m+m^2
(4)a^2-4a+4/a^2-4 (5)x^2-4x+4/x^2-4 (6)a^2+4ab/a^2b+4ab^2
(7)先化简,再求值（a^2-4)/(a-2)-3a+6,其中a=-5
(8)有三个整式x^2-2,x^2+2x+1,x^2+x,请你从中任意选择两个,将其中一个作为分子,另一个作为分母,组成一个分式,并对这个分式进行化简.
约分(9)x^2-4y^2/x^2-4xy+4y^2
约分:(1)2m(m-n)/4m(n-m)^2 (2)2m(m-n)/4m(n-m) (3)m^2-4/2m+m^2 (4)a^2-4a+4/a^2-4 (5)x^2-4x+4/x^2-4约分:(1)2m(m-n)/4m(n-m)^2 (2)2m(m-n)/4m(n-m) (3)m^2-4/2m+m^2(4)a^2-4a+4/a^2-4 (5)x^2-4x+4/x^2-4 (6)a^2+4ab/a^2b+4ab^2(7)先化简,再求值（a^2-4)/(
(1)2m(m-n)/4m(n-m)^2=2m(m-n)/[4m(m-n)^2]=1/[2(m-n)]
(2)2m(m-n)/4m(n-m) =-2m(m-n)/[4m(m-n)]=-1/2
(3)m^2-4/2m+m^2=(m+2)(m-2)/[m(m+2)]=(m-2)/m
(4)a^2-4a+4/a^2-4=(a-2)^2/[(a+2)(a-2)]=(a-2)/(a+2)
(5)x^2-4x+4/x^2-4=(x-2)^2/[(x+2)(x-2)]=(x-2)/(x+2)
(6)a^2+4ab/a^2b+4ab^2=a(a+4b)/[ab(a+4b)]=1/b
(7)(a^2-4)/(a-2)-3a+6=(a+2)(a-2)/(a-2)-3a+6=a+2-3a+6=-2a+8=18
(8)"x^2-2"应是"x^2-1"
(x^2-1)/(x^2+2x+1)=(x=1)(x-1)/(x+1)^2=(x-1)/(x+1)
(x^2+2x+1)/(x^2+x)=(x+1)^2/[x(x+1)]=(x+1)/x
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