\[\boxed{\text{187.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]
\[\textbf{а)}\ f(x);\ \ g(x) - четные\ \]
\[функции.\]
\[f( - x) = f(x);\ \ g( - x) = g(x)\]
\[y( - x) = f( - x) \cdot g( - x) =\]
\[= f(x) \cdot g(x) = y(x).\]
\[\textbf{б)}\ f(x);g(x) - нечетные\ \]
\[функции.\]
\[f( - x) = - f(x);g( - x) = - g(x)\]
\[y( - x) = - f(x) \cdot \left( - g(x) \right) =\]
\[= f(x) \cdot g(x) = y(x).\]
\[\textbf{в)}\ f(x) - четная\ функция;\]
\[g(x) - нечетная\ функция.\]
\[f( - x) = f(x);\ \ g( - x) = - g(x)\]
\[y( - x) = f( - x) \cdot \left( g( - x) \right) =\]
\[= f(x) \cdot \left( - g(x) \right) = - y(x).\]