Intergrate ln(x) with resepct to x

To integrate this, we use the product rule. Think of it as intergrate [ 1 x ln (x)]. As by the product rule we chose one to intergrate and one to differentiate. We intergrate 1 to get x. We differentiate ln (x) to get 1/x. The final answer will then be xln(x) + x + C