00:01
Problem 11 of section 7 .1 asks for the equation of a bacteria culture that initially has 400 cells and has 800 cells after one hour.
00:12
So the first thing that we need to do to solve this equation is write out the general solution for differential equations, which we know to be y of t is equal to a times e to the kt.
00:26
Now the next thing that we are going to do is we're going to go to this initial condition and use it to solve.
00:32
For a.
00:34
So to do so, we need to plug in 400 for y of 0.
00:37
We're going to set that equal to a times e to the k.
00:41
And again, as we already established, t is going to equal zero.
00:45
So what we end up with is 400 is equal to a times 1.
00:54
Because as we know, k times 0 is equal to 0, and anything to the 0th power, so all of this is just going to be 1.
01:02
So this means, that a is equal to 400.
01:05
We can get rid of this...