00:01
So what i'm looking at here, x squared minus 6x plus k, is if p and q are zeros, then there's two things i need to know is that this piece up here was factorable, and p times q is equal to k, but also if i add p and q together, that needs to equal negative six.
00:25
So let me go back to that other piece where we have three p plus two q needs to equal 20.
00:31
Just trying to use a different color.
00:33
I'll use it here.
00:35
What i can do is multiply this by negative two.
00:39
So negative two p, negative two q, and positive 12.
00:45
That way i can add straight down.
00:48
And the reality is, is when you add equal things to equal things, the result stays equal.
00:54
So these q's will cancel.
00:56
Three p plus negative two p is one p, and 20 plus 12 is 32.
01:04
But then back over here, i can plug in 32 plus q needs to equal negative six.
01:12
So what i can do is subtract that 32 over.
01:18
And let me just double check that that's negative 38 using a calculator...