Salut,
[tex]f(x)^{'}=(2\sqrt x\cdot lnx)^{'}=2(\sqrt x\cdot lnx)^{'}=2\left[(\sqrt x)^{'}\cdot lnx+\sqrt x\cdot(ln x)^{'}\right]=\\\\=2\left[\dfrac{1}{2\sqrt x}\cdot lnx+\sqrt x\cdot\dfrac{1}x\right]=\dfrac{lnx}{\sqrt x}+2\dfrac{1}{\sqrt x}=\dfrac{\sqrt x(2+lnx)}x.[/tex]
Green eyes.
