00:01
Okay, we have here then the graph of y equals 1 over x cubed.
00:05
If i draw it, it might be helpful.
00:07
So here we have x and y axes, and the graph looks like this.
00:15
Let's try again like that.
00:17
We have ascentotes along the x and y axes.
00:21
What i want is the equation of the tangent.
00:26
So let's put here at the point where x equals 3.
00:33
I want to find this green line's equation.
00:38
To do that, i want to work out the gradient at that point, and for that i will need d .y by dx.
00:45
So here, what i have is y equals 1 over x cubed, which you write as x to the minus 3.
00:55
And then, dy by dx is the gradient function.
01:00
It's minus 3, x to the minus 4.
01:04
In other words, that will be minus 3 divided by x power 4...