00:01
For question 1, we are given the function tq, which represents the total production costs as well as this point q that we need to prove it's the economic lot size that minimizes this total production costs.
00:13
So in order to do that, we will find the critical point for tq by taking the first derivative and setting that equal to zero.
00:20
So we get t prime of q equals negative fm over q squared.
00:32
This is a constants that will equal 0, and q is to the first power.
00:36
Therefore, we will just be left with k over 2 plus k over 2.
00:41
Now, this is our first derivative, and to get the critical point, we need to set this equal to 0, as that will tell us when this function changes from either increasing to decreasing or decreasing, therefore will either be a minimum or a maximum.
00:55
So 0 equals negative fm over q squared plus k over 2.
01:07
Now we can just solve this fm over q squared equals k over 2.
01:16
We're going to multiply q squared over to this side and at the same time we're going to divide to k over 2 under this side.
01:23
I'll give us 2 f f fm m over k equals q squared finally we get q equals the square root to fm over k so this is verified that our value that we are given q is in fact a critical point but we need to prove whether this is a min or a maximum we want it to be a minimum as then it would minimize the total production costs of this function so how do we do that well we need to take now the second derivative of tq at the point q, and if it's positive, this will be a minimum.
02:03
If it's negative, it'll be a maximum...