Question

12/m^2-9,4/9-3m通分 .1/x-2,1/4-x^2通分.

Answer 1

12/m^2-9,4/9-3m通分

最简公分母为3(m+3)(m-3),于是

12/(m^2-9)=36/[3(m+3)(m-3)]

4/9-3m=-4/3(m-3)=-4(m+3)/[3(m+3)(m-3)]

第二题：

1/x-2,1/4-x^2

最简公分母为(x+2)(x-2),于是

1/x-2=(x+2)/[(x+2)(x-2)]

1/4-x^2=-1/[(x+2)(x-2)]