[tex]\displaystyle\bf\\1)\\\\f(x)=x^{2} -4\sqrt{x} +Sinx\\\\f'(x)=(x^{2} )'-4\cdot(\sqrt{x} )'+(Sinx)'=2x-4\cdot\frac{1}{2\sqrt{x} }+Cosx=\\\\=2x-\frac{2}{\sqrt{x} }+Cosx\\\\\\2)\\\\f(x)=\sqrt{x} \cdot Sinx\\\\f'(x)=(\sqrt{x} )'\cdot Sinx+\sqrt{x} \cdot(Sinx)'=\frac{1}{2\sqrt{x} }\cdot Sinx+\sqrt{x} \cdot Cosx\\\\\\3)\\\\f(x)=\frac{Sinx}{x^{2} } \\\\f'(x)=\frac{(Sinx)'\cdot x^{2} -Sinx\cdot(x^{2} )'}{(x^{2} )^{2} } =\frac{x^{2} Cosx-2xSinx}{x^{4} }=\\\\=\frac{xCosx-2Sinx}{x^{3} }[/tex]