00:01
The trick to this problem is completing the square.
00:03
And the first thing i'm going to do is just use the commutative property and move things around.
00:10
Now, normally i would put a space here, but i actually do one more thing as well anyway.
00:16
Same thing with a minus y squared, minus 6y with a blank.
00:25
And i'm just going to subtract 18 to the right side, and 0 minus 18 to 918.
00:32
And what i actually have to do before i complete the square is i need to factor out the leading coefficient.
00:40
That way, my, i need to have a minus, i need to have the leading coefficient be one on each of these.
00:48
So just to make sure that your math is correct, because as you, i guess, factor out that you, like, double check that your math is correct, like 9x squared as i distribute that in.
01:02
So the process is always half of that middle number squared.
01:07
Well, negative 2 squared is 4.
01:09
So i'm going to add 4 in here.
01:11
But the quantity i'm actually adding is 9 times 4, so that's 36.
01:16
And the same thing over here, it's the same process, half of that middle number squared.
01:22
So 3 squared is 9.
01:24
But what's really happening is i'm adding a negative 9 to that side.
01:29
So i need to subtract 9 over.
01:31
So the whole point of doing this, completing the square process, is now you have a perfect square trinomial, x minus 2, x minus 2, but we just write it once.
01:43
Same thing with this piece.
01:46
Y plus 3, y plus 3 is the factored form.
01:50
And then on the right side we have 36 minus 18 is 18, minus 9 is 9...