f(x) = ln x / sqrtx
==> u=
ln x ==> du = 1/x dx
==> dv = (1/sqrtx) ==> v =
2sqrtx
==> Int u dv = u*v - INt v
du
= 2sqrtx*ln x - Int (2sqrtx/x) dx
= 2sqrtx*lnx - 2*Int 1/sqrtx dx
= 2sqrtx*lnx -
2*2sqrtx
= 2sqrtx*lnx - 4 sqrtx
=
2sqrtx(lnx -2)
(((To prove tthat Int 1/sqrtx dx = 2sqrtx
:
Let u= sqrtx ==> du = (1/2sqrtx)
dx
==> du = 1/2u dx
==>
2u du = dx
==> Int 1/sqrtx dx = Int 1/u * 2u du = Int 2 du =
2u = 2sqrtx ))))
==> Int lnx/sqrtx =
2sqrtx*(lnx -2).
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