00:02
All right, we have the product, x plus 4 times x minus 8.
00:16
And we want to know when this is going to be less than 0.
00:20
Normally we would factor first, but that's already done for us.
00:23
So the first thing we have to do here is let each factor equals 0 and find our roots.
00:32
Subtract 4 from each side, you get x equals negative 4.
00:39
And at 8 to each side, you get x equals 8.
00:43
So that's where our roots are going to be.
00:45
Now, we know when we are finding solution sets for quadratic inequalities, our solution set will either be the values between the roots or to the left and right of the roots, right? so it's going to be one of these two possibilities.
01:07
We have to determine which we have going on here.
01:14
What we know is that we have roots at negative 4 and 8.
01:23
What i don't know is whether i'm going to be between the negative 4 and the 8 or to the left and right.
01:31
So we're going to pick a test point, and one that's easy to test that's between negative 4 and 8 is 0...