00:01
Okay, here we have a function f -of -x that we want to get into standard form, much like m of x up here.
00:09
Okay, so the first thing i noticed that we have a negative sign in front of our x -squared term.
00:13
So i'm going to divide everything by negative one on both sides.
00:17
And now we have x squared plus 4x minus 1.
00:21
Now, these two terms are familiar.
00:24
They're also the same first two terms from x minus x plus two quantity squared.
00:31
And so the constant term of that when we expended out is going to be plus 4, but we have a negative 1 here.
00:38
So we're going to add 5 to both sides, and we end up with 5 minus f of x, is equal to, now we can write this as x plus 2 quantity squared.
00:50
Now, i'm going to move this 5 over here, subtract it from both sides, and now we have a negative sign.
00:59
So i'm going to divide the entire thing by negative 1 again, so that we have negative x plus 2, quantity squared plus 5.
01:08
And that's our standard form.
01:10
Now, the good thing about standard form, it allows us to write our vertex very easily as hk.
01:15
So here we have negative 2 .5.
01:18
Be careful with the signs when doing that...