00:01
Okay, so i have a swimming pool here.
00:04
It's really nice and pretty.
00:09
And we're swimming in it.
00:12
And the dimensions of the swimming pool are 30 by 12.
00:16
Now, we have added a walkway around the swimming pool.
00:22
Now, it hasn't said this explicitly, but i think it's fair to assume that we are adding the same amount to all four sides.
00:32
So we're adding a certain number of feet to each side of the pool.
00:39
So i'm going to say that this is going to be x, labeled as x.
00:44
So the area is going to be, the total area will be 1 ,288.
00:49
So area is calculated as length times width.
00:53
So the length of our pool will be 30 plus some value x.
01:00
The width will be 12 plus some value x.
01:05
And that will equal 1 ,288 square feet.
01:10
So let's start multiplying here.
01:14
So 30 times 12 is going to be 360.
01:18
So first, we're going to do foiling here, or you can do the box method.
01:24
30x, 12x.
01:27
So this will be 360, 30x, 12x, and then x squared.
01:36
So if you want to call it foil, if you want to call it the box method, whatever you do, as long as you end up with this, you can call it whatever makes you and your teacher happiest.
01:48
So 360 plus 12x plus 30x plus x squared.
01:56
Combine like terms.
01:58
Our like terms are 12x and 30x.
02:01
So we're going to have 360 plus 12 plus 30.
02:07
12x plus 30x is 42x, plus x squared equals 1 ,288.
02:14
Now the first step into factoring is going to be to set the equation equal to 0.
02:20
So we need to subtract 1 ,288 from both sides.
02:23
And as i do that, i'm going to reorder this equation to be x squared plus 42x plus 360 minus 1 ,288 equals 0.
02:39
Now, i'm going to admit that i'm human, and i'm sure you are too.
02:43
So i'm going to use a calculator for this.
02:46
So let's come out to my calculator, maybe.
02:57
So this is going to be 360 minus 1 ,288.
03:01
So i have 928 here.
03:04
So let's come back.
03:06
I'm going to have x squared plus 42x minus 928.
03:16
Now, i am a math teacher, and i'd like to think i'm pretty good at math.
03:21
However, i don't know all the factors to 928 off the top of my head.
03:26
We could do the quadratic formula, but i really am not in the mood to do all that squaring and multiplying.
03:33
So i'm going to help you...