原式= ?(m?3) 2(m?2) ÷[ (m+2)(m?2)?5 m?2 ]= ?(m?3) 2(m?2) ÷ m2?9 m?2 = ?(m?3) 2(m?2) ? m?2 (m+3)(m?3) =- 1 2(m+3) ∵2m-4≠0，（m+3）（m-3）≠0，m≠2，m≠±3，∴取m=1，原式=- 1 2×(1+3) =- 1 8 ．
