替换后底数变为1.x→0,y→2时ln[sin(xy)/(xy)]/x^2→{2x/sin(2x)*(1/2)(2xcos2x-sin2x)/x^2}/(2x)→(2xcos2x-sin2x)/(4x^3)→(2cos2x-4xsin2x-2cos2x)/(12x^2)→8x/12x=2/3.,∴[sin(xy)/(xy)]^(1/x^2)=e^{ln[sin(xy)/(xy)]/x^2}→e^(2/3),
x趋于零分母为零,不成立。不能用0/0