一种方法是括号内先通分,再与括号外分式相乘：
={3x*(x+2)/(x^2-4 )-x*(x-2)/(x^2-4 )}*(x^2-4 )/x =2x+8
另一种是将括号外分式乘进去,再相减：
=3x/(x-2)*(x^2-4 )/x -x/(x+2)*(x^2-4 )/x=2x+8