00:01
All right, so we have the first of our word problems.
00:03
It gives us a scenario with a concrete cutting machine and a function of the cost of running that machine based on the number of minutes that it is running.
00:14
Now it asks us, and the keyword here, is that it does ask us for what number of minutes is the cost of running the machine a minimum, and what is the minimum cost? so we're looking for the minimum minutes, and we're looking for a minimum cost.
00:41
So the easiest way to set this up is graph it.
00:48
I mean, you could complete the square and find the vertex point, because that would tell you your minimum or maximum point, but we can also graph it, and in this case, we're going to use the minimum.
01:02
So with the graphing with this one, you have to be really careful because your window has to be big enough to be able to see the graph.
01:08
And if we pull up the graph here, we can see that the graph is in really, really, really large numbers, which makes sense because we can see it ends with 655, so it's going to be really, really, really large.
01:27
So when we do graph it, we need to make sure we can actually see the graph.
01:34
So there's our graph right there.
01:36
We're looking for this low point right here.
01:38
That would give us our minimum.
01:40
To do that, remember you go into second trace...