A graphing device is recommended.

A function is given.

$f(x)=6+x+x^2-x^3$

$($a$)$ Find the local maximum and minimum values of the function and the value of $x$ at which each occurs. State each answer rounded to two decimal places.

$($b$)$ Find the intervals on which the function is increasing and on which the function is decreasing. State each answer rounded to two decimal places. $($Enter your answers using interval notation.$)$

increasing

decreasing