Question 755723
The factored form as you have is very convenient for finding the solution set.  The critical values are at x equal to 4, 5, and 6.  The intervals to check are these:


(-infin, 4)
(4, 5)
(5, 6)
(6, +infin)


Test -5.  Let x = -5.
(-)(-)(-)=(-)<0?  TRUE.


Test 4.5
(+)(-)(-)=(+)<0?  FALSE


Test 5.5.
(+)(+)(-)=(-)<0?  TRUE.


Test x=7.
(+)(+)(+)=(+)<0?  FALSE.


Each of those tests correspond to the item corresponding to the listed intervals.

Solution set is (-infin, +4) AND (+5, +6).