How do I integrate ln(t)/t dt. I know that the answer is 1/2 ln(t)^2 + C, but I don\'t know how to arrive at that. I tried integrating by parts and that didn\'t seem to work. Solution put lnt = y differeantiating with t, 1/t = dy/dt now, int [ lnt/t dt ] = int [ y/t x tdy ] = int [ y dy ] = y^2/2 + c put y = lnt we get , I = (lnt)^2/2 + c.