dx
sqrt(x)=t
x=t^2
dx=[b]2tdt[/b]
x_(1)=4 ⇒ t_(1)=sqrt(4)=2
x_(2)=9 ⇒ t_(1)=sqrt(9)=3
= ∫^(3)_(2) t*([b]2tdt[/b])/(t-1)=2 ∫^(3)_(2)( t^2-1+1)/(t-1)dt=2 ∫^(3)_(2) (t+1)+2 ∫^(3)_(2) dt/(t-1)=
=(2*(t^2/2)+2t+2ln|t-1|)|^(3)_(2)=3^2+2*3+2ln2-2^2-2*2-2ln1=
=7+2ln3