00:01
Here on this problem, we want to use the graph of the polynomial that we've been given to estimate the year in which carbon dioxide concentration will be 400.
00:10
And so let's use a graph in calculator here, so i'm going to use desmos.
00:14
And so graph this, we have negative 1 over 2 ,400, t to the 3rd, plus 1 over 20 t squared.
00:26
Actually, i need to use x here on desmos, so i'll use x to the 3rd, plus 1 over 20.
00:33
X squared plus 7 over 6x plus 340.
00:48
Now, as you can see, i'm going to need to change my window here.
00:51
And they tell us to use between 0 and 60 for t.
00:55
And so let's change that window here on the x -axis, because x is what i call the t.
01:01
Let's go 0 to 60.
01:04
And for our y -axis here, let's change this to 0 to 500.
01:21
And so that's the only piece of the graph that we're going to need here...