Consider the function f$($x$)=(3$x$+5)/(4$x$+1).$ For this function there are two important intervals:

and

where the function is not defined at

$.$

Find

For each of the following intervals, tell whether

is increasing $($type in INC$)$ or decreasing $($type in DEC$).$

:

Note that this function has no inflection points, but we can still consider its concavity. For each of the following intervals, tell whether

is concave up $($type in CU$)$ or concave down $($type in CD$).$

: