2mn/4m²-9与2m-3/2m+3通分要过程

3/(5x²+5x-10)=3/[5(x+2)(x-1)]=3(x-3)/[5(x+2)(x-1)(x-3)]
(x+1)/(x²-x-6)=(x+1)/[(x-3)(x+2)]=5(x+1)(x-1)/[5(x+2)(x-1)(x-3)]
(2-x)/(x²-4x+3)=(2-x)/[(x-3)(x-1)]=5(2-x)(x+2)/[5(x+2)(x-1)(x-3)]
分子之和=3(x-3)+5(x^2-1)-5(x^2-4)=3x-9+5x^2-5-5x^2+20=3x+6

约分：（49--x^2)/2x+14)=(7+x)(7--x)/2(x+7)
=(7--x)/2
2.题目有错.
通分：a/2b^2=3a^2c/6ab^2c 2/(9--3a)=--2/3(a--3)=--2(a+3)/3(a+3)(a--3)
1=6ab^2c/6ab^2c (a--1)/(a^2--9)=(a--1)/((a+3)(a--3)
--3a^2=--18a^3b^2c/6ab^2c =3(a--1)/3(a+3)(a--3).
5/6abc=5b/6ab^2c.

3a分之2与-4ab的平方分之3通分
2/3a -3/4ab^2
=2ab/3ab^2-3/4ab^2
=8ab/12ab^2 -9/12ab^2
=(8ab-9)/12ab^2

1.2mn/4m²-9
2.2m-3/2m+3= （2m-3）²/（2m+3）（2m-3）=（2m-3）²/4m²-9