00:01
Okay, so we're going to solve x squared minus 2x minus 8 equals 0.
00:07
That's a quadratic equation.
00:09
And we're going to try, there's a number of ways of solving it, but we're going to try solving it by factoring.
00:15
And so we're factoring a trinomial here.
00:17
So trinomial just means that there's one, two, three pieces to it.
00:22
And what we're looking for here are the factors that multiply to negative 8 and, add to negative two.
00:42
Okay, so we can start by just creating a list of numbers that multiply to negative eight.
00:46
So it would be one and negative eight, two and negative four.
00:53
Then you could say negative four and two.
00:56
Oops, that would be the same one.
00:58
Sorry, i went to say four and negative two and eight and negative one.
01:08
And so we go through this list and we look for the ones that add to negative 2.
01:13
And so that would be these two here.
01:16
And so this just becomes x plus 2, x minus 4 equal 0.
01:24
Okay, so that's called factoring.
01:27
And now we can set each piece equal to 0.
01:30
So you can say x plus 2 equals 0 or x minus 4 equals 0...
