分子分母同乘y1y2
解：（2p/y1*y1y2+2p/y2*y1y2）/(y1y2-4p^2/y1y2*y1y2)=(2py2+2py1)/(y1y2-4p^2)=2p(y2+y1)/(y1y2-4p^2)=2p(y1+y2)/(y1y2-4p^2)答：答案是2p(y1+y2)/(y1y2-4p^2)。
