If a + $\alpha$ = 1, b + $\beta$ = 2 and $af(x) + \alpha f\left( {{1 \over x}} \right) = bx + {\beta \over x},x \ne 0$, then the value of the expression ${{f(x) + f\left( {{1 \over x}} \right)} \over {x + {1 \over x}}}$ is __________.