00:01
Here we're given the equation we want to solve.
00:03
We have negative 2x squared plus 8x plus 2 equals 4.
00:09
And we want to solve this using completing the square.
00:12
So the first thing i'm going to notice is the leading coefficient here is not 1.
00:16
So that means we can't really do it.
00:18
So let's just divide everything by negative 2 to make that a 1.
00:22
So that gives me x squared minus 4x minus 1 is equal to negative 2.
00:28
Now i'm going to add 1 to get x squared minus 4x is equal to negative 2 plus 1 is negative 1.
00:34
Now we're ready to complete the square.
00:36
So i'm going to take the x squared minus 4x, and i'm going to add what i like to call the magic number.
00:43
And i can only do that if i add it on the other side as well.
00:48
Now this magic number is going to be one that we choose very carefully.
00:51
And i'm not going to get into exactly why in this video, but if you'd like to ask, you're welcome to...