00:01
In this problem, you're given the length of a rectangle is four more than the width.
00:07
And the area is 21 square inches.
00:11
All right.
00:12
So i have on the side, i let that side equal x, and we'll call that the width.
00:20
And then we're, so this is the width and the length.
00:25
All right, so it says the length is four more than the width, so i made that x plus four.
00:32
Write your area formula for a rectangle.
00:35
This length times width.
00:38
So we'll substitute in 21 for the area.
00:43
The length is x plus 4.
00:47
And the width is x.
00:51
All right, to start simplifying, we'll go ahead and distribute on this side.
01:01
So we'll have 21 is equal to x squared plus 4x.
01:08
All right, so since this is what we call a quadratic equation with the x squared, we need 0 on one side.
01:23
So we're going to go ahead and subtract the 21 on both sides...