\[1)\ y = \sqrt{x^{2} + 1} \bullet ctg\ 4x;\]
\[= \frac{x \bullet ctg\ 4x}{\sqrt{x^{2} + 1}} - \frac{4\sqrt{x^{2} + 1}}{\sin^{2}{4x}}.\]
\[2)\ y = e^{\frac{x}{2}} \bullet \sin^{3}{3x};\]
\[= \frac{1}{2}e^{\frac{x}{2}} \bullet \sin^{3}{3x} + 9e^{\frac{x}{2}} \bullet \sin^{2}{3x} \bullet \cos{3x}.\]
\[3)\ y = \sqrt{x} \bullet \sin{4x};\]
\[y^{'}(x) = \frac{1}{2\sqrt{x}} \bullet \sin{4x} + 4\sqrt{x} \bullet \cos{4x}.\]
\[4)\ y = e^{3 - 2x} \bullet \cos(3 - 2x);\]