## geerky42 2 years ago $\Large \int \dfrac{dx}{\ln x}$

1. inkyvoyd

set u=ln x then du/dx/u

2. inkyvoyd

you should be able to figure it out with u-sub

3. geerky42

du/dx/u?

4. geerky42

but then how can I use du? There is no place to put du

5. inkyvoyd

I may have overlooked this >.< gimme a minute getting some paper

6. Kanwar245

Integration by parts?

7. Xavier

It can't be expressed in terms of other functions. That integral is the basis of the logarithmic integral function $li(x)=\int_{0}^{x}\frac{dt}{ln(t)}$

8. Kanwar245

u = 1/ln x, dv = 1

9. inkyvoyd

No, I'm correct.

10. inkyvoyd

u=lnx du=dx/u Int 1/u dx=int du

11. geerky42

Please explain more clear @inkyvoyd How to use u-substitution?

12. inkyvoyd

int du=u

13. inkyvoyd

gimme a minute lemme use latex

14. geerky42

well then i get u = u it dont do anything.

15. geerky42

I think @Xavier is correct, it can't be expressed

16. inkyvoyd

yes, xavier is in fact correct (facepalm)

17. inkyvoyd
18. geerky42

Thank you, here's gif

19. inkyvoyd

LOL