[（m+1）（m+3）（2m-m²）] ÷ [ （m³+m²）（m-2）（m-3）]
= [ (m+3) (-1) ] ÷ [ m (m-3) ]
= ( - 5/3) ÷ [ (-4/3) (-13/3)]
= - 15/52化简后求值！！！！前面就是化简的过程。约去相同的项： m(m+1)(m-2)