00:02
So for this problem we're given two equations.
00:05
A is negative 2x plus 5p equals 75 and b is 6x plus 4p equals 900 where x is the number of items and p is the price.
00:18
So the first thing i want to know which of these two is the demand function.
00:21
So i'm going to solve both of these for p to get kind of a better idea of what it is that's happening here.
00:26
So if i solve this first one for p i'm going to get 5p equals 2x plus 75.
00:36
I'm going to divide by 5 so p equals 2 fifths x plus 15.
00:47
And then for this second one here if i solve for p i'm going to get 4p equals negative 6x plus 900 and divide by 4p is going to equal negative 3 over 2x plus 2 and 2 and 5 225.
01:08
I think let me check just to be sure.
01:16
Yep okay so first we want to know which one is the demand function.
01:20
Well if you think about just the stereotypical like we've got price and we've got quantity which for us is x.
01:30
The supply curve is the one that goes like this.
01:34
This is supply and the demand if it's free you probably have the most demand and then as your price increases then your demand like how many you sell goes down.
01:52
So when the price gets bigger the number sold so x gets smaller.
01:59
So this is your demand function.
02:05
And so demand is going to end up being equation b because demand functions have negative slopes if they're in terms of p or in terms of x...