1/2x趋于无穷则sin(1/2x)在[-1,1]震荡即有界所以xsin(1/2x)趋于01/xsin2x=2sin2x/2x所以极限是2×1=2所以极限=0+2=2
=[e^2xlnx-1]/x=2xlnx/x=-∞
