00:01
So we've got our equation here, p of x equals 8x plus nt1 .3x squared minus 0 .0 .03x to the power of 3 minus 3172.
00:10
X equals the amount of blenders that are sold and p equals the profit.
00:15
So part a here is asking, they make a loss when just a few blenders are sold.
00:22
So it's asking how many blenders must have been produced to break even.
00:26
Okay.
00:27
So we're essentially need to find here.
00:31
At what point does the profit start to become greater than zero? and so it's going to be minus.
00:47
We'll put this into, oh, so essentially we need to find our, okay, we're going to draw, we're going to start off by drawing a graph, i think.
00:59
Yeah, so we're going to start off by drawing a graph.
01:03
I think i can see where this is heading, yeah.
01:06
So we've got a negative cubic graph here.
01:10
So we're going to draw this.
01:13
So it's going to come from above.
01:16
We're going to get one turning point roughly here maybe and then another turning point up here.
01:21
And we need to find this point here.
01:26
I imagine though the, sorry, i imagine this green line here would probably be more over here in this example because you can't really build negative things.
01:37
So we need to find, sorry, it'll probably be round about there when it starts to dip.
01:45
We need to find this point here.
01:48
What is this point? so we're going to find our second x intercept.
01:56
So when x equals zero.
01:59
So we're going to set the equation equal to zero.
02:02
I'm going to solve it.
02:05
So p of x equals.
02:07
And we can see on the graph, that it's actually going to be the second time.
02:12
That's why the graph is so important here.
02:14
We're not going to take our first, and we're not going to take our smallest value.
02:18
We're going to take our second largest value.
02:21
And that is going to be our answer.
02:24
So we're going to set that equal to zero, and it's going to be minus 0 .0 .11 .13x cubed, plus 0 .3x squared, plus 8x ,x minus 3 .6.
02:40
That's set equal to zero.
02:42
I'm going to get three x values here.
02:46
I'm just going to put this in my calculator.
02:48
If you don't have a calculator, then the quadratic method.
02:52
Actually, that won't work here.
02:53
You'd have to factorize, and that would be quite difficult.
02:57
I don't think they just make your answer this without a calculator to solve it for you.
03:02
So i'm just putting in the numbers here.
03:04
Not 1 .3.
03:07
0 .3 .8 minus 372.
03:13
There we go, that should be correct.
03:16
So we get our first intercept at x equals 250, actually.
03:26
Okay, so that's at 250 blunders.
03:31
That's probably not going to be our first intercept.
03:33
We got our first intercept at 25.
03:35
That's our second intercept.
03:37
Okay, so we get our first intercept at minus 45 .22.
03:44
So that is our first value over here.
03:48
We'll do this, we'll call it a coordinate this...