Salut,
[tex]f(x)^{'}=(\sqrt x-2+\sqrt{10}-x)^{'}=(\sqrt x)^{'}+(-2)^{'}+(\sqrt{10})^{'}+(-x)^{'}=\\\\=\left(x^{\frac{1}{2}}\right)^{'}+0+0+(-1)=\dfrac{1}2\cdot x^{\frac{1}2-1}-1=\dfrac{1}2\cdot x^{-\frac{1}2}-1=\dfrac{1}{2\cdot\sqrt x}-1.[/tex]
Green eyes.
