上式化简=2x/(x-2)(x+2)-1/(x-2)(提取公因式)
=1/(x-2）乘以[2x/(x+2)-1]
= 1/(x-2）乘上（2x-x-2）/(x+2) (通分)
=1/(x-2）乘上(x-2）/(x+2) （约分）
=1/ (x+2)（将x带如等式）
=2/5