You can put this solution on YOUR website!
make the inequality sign an equal sign.
x=-16, x=13, x=-8
Test above, below and between the above numbers.
when x=-20 then y=-1584
when x=-10 then y=276
when x=-7 then y=-180
when x=14 then y=660
X(-16, -8) U (13, Infinity) This means that f(x)>0 when x is between -16 and -8 and also when x>13