Period of $f(x)=\{x\}+\left\{x+\frac{1}{3}\right\}+\left\{x+\frac{2}{3}\right\}$ is equal to (where $\{\cdot\}$ is fractional part function)

The domain of $$f(x)=\sqrt{\log \frac{1}{4}\left(\frac{5 x-x^2}{4}\right)}+{ }^{10} C_x$$ is

The quotient of the identity function by the reciprocal function is given by

Which of the following is not a function?