3-m 2m-4÷(m+2-5 m-2);3-m/2m-4÷(m+2-5/m-2); /是分数线,

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3-m 2m-4÷(m+2-5 m-2);3-m/2m-4÷(m+2-5/m-2); /是分数线,
3-m 2m-4÷(m+2-5 m-2);
3-m/2m-4÷(m+2-5/m-2);
/是分数线,

3-m 2m-4÷(m+2-5 m-2);3-m/2m-4÷(m+2-5/m-2); /是分数线,
(3-m)/(2m-4)÷[m+2-5/(m-2)]
=(3-m)/(2m-4)÷[(m^2-4-5)/(m-2)]
=(3-m)/(2m-4)÷[(m^2-9)/(m-2)]
=(3-m)/(2m-4)÷[(m-3)(m+3)/(m-2)]
=(3-m)/(2m-4)*(m-2)/(m-3)(m+3)
=-(m-3)/2(m-2)*(m-2)/(m-3)(m+3)
=-1/2(m+3)
=-1/(2m+6)