00:01
We want to solve this initial value problem here.
00:04
So all that is really saying is we want to find some function r, that when we take the derivative of it twice, we get 2 over t cubed.
00:14
And when we plug in 1 into its derivative, we get an output of 1.
00:21
And when we plug 1 into the original function, we get an output of 1.
00:28
So let's go ahead and first integrate this.
00:30
So we can figure out what our first derivative of this function is going to be.
00:35
So i'm going to rewrite this as just r prime when we integrate it as opposed to writing dr by dt.
00:41
Now to integrate this, well, let's first go ahead and factor out that two, and we can rewrite 1 over t cubed as t to the negative third.
00:51
And now this just follows from power rule.
00:54
So power rule says we add one to the power, and then divide by its new power, and then we add a constant to it.
01:02
So we can go ahead and cancel out those twos.
01:06
So it should be negative 1 over t squared plus c.
01:10
And so this is equal to our first derivative.
01:13
Now they tell us when we plug in 1, we should get an output of 1.
01:17
So let's go ahead and do that.
01:19
So we have 1 is equal to just negative 1 plus c...