∫ln(2x+1)dx
=1/2∫ln(2x+1)d(2x+1)
=(2x+1)ln(2x+1)/2-1/2∫(2x+1)dln(2x+1)
=(2x+1)ln(2x+1)/2-1/2∫(2x+1)*1/(2x+1)*(2x+1)'dx
=(2x+1)ln(2x+1)/2-1/2∫2dx
=(2x+1)ln(2x+1)/2-x+C