What is int ln x / sqrtx dxlnxxdx?

1 Answer
May 3, 2018

2sqrtx(lnx-2)+c2x(lnx2)+c

Explanation:

intlnx/sqrtxdx=intlnx/color(blue)(2sqrtx)(2color(blue)(dx))lnxxdx=lnx2x(2dx)

Substitute sqrtx=ux=u

  • x=u^2x=u2

  • 1/(2sqrtx)dx=du12xdx=du

== intlnu^color(red)(2)/cancel(u)(2cancel(u)du) =

int2*2lnudu =

4intlnudu =

4(ulnu-u)+c =

4(sqrtxlnsqrtx-sqrtx)+c =

4(1/2sqrtxlnx-sqrtx)+c =

2sqrtx(lnx-2)+c ,

cinRR