计算:12/m^2-9-2/m-3

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计算:12/m^2-9-2/m-3

计算:12/m^2-9-2/m-3
计算:12/m^2-9-2/m-3

计算:12/m^2-9-2/m-3
=12/(m+3)(m-3)-2/(m-3)
=(12-2(m+3))/(m+3)(m-3)
=(6-2m)/(m+3)(m-3)
=-2/(m+3)

计算:12/m^2-9-2/m-3

=(12-2(m+3))/(m+3)(m-3)
=(6-2m)/(m+3)(m-3)
=-2/(m+3)

12/m^2-9-2/m-3?应该是12/(m^2-9)-2/(m-3)吧?
如果是的话:

12/(m^2-9)-2/(m-3)
=12/[(m+3)(m-3)]-2/(m-3)
=12/[(m+3)(m-3)]-2(m+3)/[(m-3)(m+3)]
=[12-2(m+3)]/[(m+3)(m-3)]
=(12-2m-6)/[(m+3)(m-3)]
=2(3-m)/[(m+3)(m-3)]
=-2(m-3)/[(m+3)(m-3)]
=-2/(m+3)