\[\boxed{\mathbf{700}\mathbf{.}}\]
\[1)\ y = \cos{3x};\]
\[y( - x) = \cos( - 3x) =\]
\[= \cos{3x} = y(x);\]
\[Ответ:\ \ четная.\]
\[2)\ y = 2\sin{4x};\]
\[y( - x) = 2\sin( - 4x) =\]
\[= - 2\sin{4x} = - y(x);\]
\[Ответ:\ \ нечетная.\]
\[3)\ y = \frac{x}{2}\text{\ t}g^{2}x;\]
\[y( - x) = \frac{- x}{2} \bullet tg^{2}( - x) =\]
\[= - \frac{x}{2} \bullet ( - tg\ x)^{2} =\]
\[= - \frac{x}{2}\text{\ t}g^{2}x = - y(x);\]
\[Ответ:\ \ нечетная.\]
\[4)\ y = x\cos\frac{x}{2};\]
\[y( - x) = - x \bullet \cos\left( \frac{- x}{2} \right) =\]
\[= - x\cos\frac{x}{2} = - y(x);\]
\[Ответ:\ \ нечетная.\]
\[5)\ y = x\sin x;\]
\[y( - x) = - x \bullet \sin( - x) =\]
\[= - x \bullet \left( - \sin x \right) = \sin x = y(x);\]
\[Ответ:\ \ четная.\]
\[6)\ y = 2\sin^{2}x;\]
\[y( - x) = 2 \bullet \sin^{2}( - x) =\]
\[= 2 \bullet \left( - \sin x \right)^{2} = 2\sin^{2}x = y(x).\]
\[Ответ:\ \ четная.\]