00:01
All right, so we're looking at yolanda's closet here.
00:02
Now, x is what i'm going to call the width.
00:06
And it says the length is two more, so plus two, two more than twice the width.
00:12
And so that's where we get 2x plus 12, two more than twice the width.
00:16
And then the diagonal is 13.
00:17
And so that's where that comes from there.
00:18
The diagonal is 13.
00:21
Now because our closet is a rectangle, we use pythagorean theorem here.
00:25
And that tells us x squared plus 2x plus 2 squared.
00:32
Is equal to 13 squared.
00:34
And you're just setting up with that grand theorem with this because that 13 is the hypotenuse of that right triangle.
00:41
And so then this is x squared plus, right, 2x plus 2 squared.
00:44
You need to take 2x plus 2 times 2x plus 2.
00:48
That's how you square something.
00:50
And then foil that out.
00:51
And so that's going to be 4x squared plus 8x plus 4.
01:01
And then equals 169 on the other side, whenever you take 13 and square it.
01:06
Again, we have a quadratic to solve now.
01:09
And so to solve a quadratic, we need to combine like terms first, and then get it equal to zero.
01:14
X squared plus 4x squared is 5x squared, plus 8x, and then take your 169 over.
01:25
It would be negative 165 equals zero...