3. Let $f(x)$ be defined in the interval $(-1,1)$. Then $f(x)$ can be expressed as the sum of an even function $g(x)$ and an odd function $h(x)$, where $g(x)=$ $\qquad$ ,$h(x)=$ $\qquad$ .
According to the problem, $\left\{\begin{array}{l}f(x)=g(x)+h(x), \\ f(-x)=g(-x)+h(-x)=g(x)-h(x)\end{array} \Rightarrow\left\{\begin{array}{l}g(x)=\frac{f(x)+f(-x)}{2}, \\ h(x)=\frac{f(x)-f(-x)}{2} .\end{array}\right.\right.$