cos2xsin3x

来源：学帮网编辑：学帮网时间：2024/06/02 15:08:50

设f(x)=(sin2xcos3x+cos2xsin3x)lnx,则f'(π/2)=f(x)=(sin2xcos3x+cos2xsin3x)lnx=sin(5x)lnxf'(x)=5cos(5x)lnx+sin(5x)/x;代入得2/π