Example: Find the solution to
.
Solution: First, we recognize that this is a linear equation. Indeed, we have
Therefore, the integrating factor is given by
.
Since , we get
Hence, the general solution is given by the formula
We have
The details for this calculation involve the technique of integrating rational functions. We have
Hence, the only difficulty is in the integral . Here we will use integration by parts. We will differentiate t and integrate . The details are left to the reader. We have
Therefore, we have
,
which clearly implies
The general solution can also be rewritten as
Finally, the initial condition y(0) = 0.4 gives C = 0.4. Therefore, the solution to the IVP is