For the first interval, we would have a negative infinity to negative three. We
use parentheses on each end, since we don't include these values. The
right-hand side would be four comma infinity. This would be the second
interval. Be sure to include parentheses here, because we can't include these
two values. Nice work if you remembered interval notation. And, just to be even
more certain that we're right, we can choose any number in either of these
intervals, and they should check in our inequality. So, if I chose x equals 12,
I know that's between 4 and positive infinity. So I could plug in 12 for x, and
then I would get the value 120. We know 120 is greater than 0, which means that
this statement is true. This quick check just reinforces that we have the
correct intervals on either side. It's usually a good idea to test a couple
numbers to make sure that you have the correct interval.
