00:01
In this question, we're asked to show a couple of things involving economics.
00:06
The first thing we want to do is we want to show if the profit function, p of x is a maximum, then we have the marginal revenue equal to the marginal cost.
00:18
And then the second thing we want to do is we want to prove that.
00:22
We want to find out the value that will maximize the profit given a cost function and given a demand function.
00:32
Okay, so let's see.
00:35
Remember that profit, profit is defined as revenue minus the cost.
00:45
So what we're going to do is we now will differentiate this entire thing with respect to x, the number of units being produced.
00:54
And doing it term -wise, it just results in, you just have the following.
01:10
Since the profit's continuous, the derivative of the profit is zero when you have a local maximum.
01:18
So we can set this equal to zero, in fact, and just prove that the marginal revenue, r prime of x, equals the marginal cost, which is c prime of x.
01:32
That's how it works.
01:36
Now, the second part is we're given a cost function, and it's equal to 16 ,000 plus 500x minus 1 .6x squared plus 0 .004x cubed...