∫ lnx / x^1/2 dx=2∫lnxd[x^(1/2)],利用分步积分得到：=2lnx*x^(1/2)-2∫x^(1/2)dlnx=2x^(1/2)lnx-2∫x^(1/2)/x dx=2x^(1/2)lnx-2∫x^(-1/2)dx=2x^(1/2)lnx-4x^(1/2)+c
1/x^(3/2)-1/2*ln(x)/x^(3/2)
分部积分法 u=lnx v=2x^1/2
