Integrate lnx

This requires your knowledge of integration by parts. The trick here is that lnx can also be written as lnx*1 (as any term multiplied by 1 is itself). We set u=lnx and dv/dx equal to 1. Hence from this we can write du/dx = 1/x and v =x. Now, we can apply the integration by parts formula to lnx, which will give us xlnx - x + c