The domain of the function $$f(x) = \sqrt {{{\cos }^{ - 1}}\left( {{{1 - |x|} \over 2}} \right)} $$ is

For what values of x, the function $$f(x) = {x^4} - 4{x^3} + 4{x^2} + 40$$ is monotone decreasing?

The minimum value of $$f(x) = {e^{({x^4} - {x^3} + {x^2})}}$$ is

The period of the function f(x) = cos 4x + tan 3x is