( x?4 x?2 ?2)÷ 2x x2?4 = x?4?2(x?2) x?2 ÷ 2x (x+2)(x?2) = ?x x?2 ? (x+2)(x?2) 2x =- x+2 2 ，当x=-3时．原式=- ?3+2 2 = 1 2 ．
