00:01
All right, we have a cube.
00:03
That means all the edges are the same length.
00:08
All the sides are the same size.
00:10
The volume of the cube is decreasing at a rate of two meters cube per minute.
00:15
And they want us to find the rate of change of an edge when the volume is 125.
00:21
All right, here comes a cube.
00:27
Its volume is decreasing at a rate of two meters cube per minute.
00:36
So, okay, we'll write that in a minute.
00:39
We want to find the rate of change of the edge when the volume is 125.
00:43
So we need a formula that relates the volume and the edge of a cube.
00:49
Well, first of all, let's give that edge of name.
00:51
How about x? if that's the front edge, that's also the side edge and this height here.
01:00
All right, how do you find the volume of a cube? well, you multiply length times width times height, which gives you x to the third power or x cubed...