00:01
In this problem, we are given two equations.
00:03
The first equation models the supply.
00:06
The second equation models demand.
00:08
And for these variables, q are the number of units that we are requiring.
00:15
P is the price.
00:16
Now, we want to find the equilibrium demand and supply, which means when are these two equations equal to each other? so let's put that together.
00:25
They're both solved for p.
00:27
So let's set our two equations equal to each other.
00:37
Okay, we need to get rid of these radicals in order to solve.
00:41
So i am going to square both sides of this equation.
00:46
On the front side, on the left, i'm going to get 0 .1q plus 9, minus 4 times this radical, plus 4.
01:00
On the right -hand side, squaring my radical just gives me what was underneath.
01:06
Now, i need to put together my like terms as much as i can.
01:11
Eventually have the radical on one side, everything else on the other.
01:18
Let me start with the radical over on the left -hand side.
01:26
Well, i have 9 plus 4, which is 13.
01:30
When i subtract that from the other to the other side, that gives me 12.
01:34
And i have a 0 .1q, which i bring over, will be minus 0 .2 q.
01:41
And let me divide everything by negative 4.
01:47
Keep my numbers as small as possible.
01:49
So when i divide the right -hand side by negative 4, i end up with 0 .05q minus 3.
01:59
Okay, one more time i need to square both sides to get rid of my radical.
02:05
On the left, squaring the radical gives me what was underneath.
02:10
And i will have to foil or expand this binomial on the right -hand side.
02:15
That gives me 1 -2 -0's .0025 q squared.
02:23
Minus 0 .3q plus 9.
02:28
Okay, well, i have a plus 9 on both sides, so i can subtract 9 and get those to cancel each other out...