Mathematics Department

Textbook Contents

Warning: MathJax requires JavaScript to process the mathematics on this page.
If your browser supports JavaScript, be sure it is enabled.

Separable Equations

Additional Examples

Solve the following initial value problem, $$\begin{align} \frac{dy}{dx} &= \frac{\exp(-y)}{2x + 4}\\ y(0) &= 2 \end{align}$$This is a separable equation. First we find the general solution following the paradigm.

  1. Separate the variables $$ \exp(y) dy = \frac{dx}{2x + 4} $$
  2. Integrate both sides $$ \exp(y) = (1/2)\log|2x + 4| + C $$
  3. Solve for y (if possible)

    We simplify the expression to obtain the general solution $$ y = \log((1/2)\log|2x + 4| + C) $$

  4. Check for singular solutions

    Since we never divided by anything that could be 0, there are no singular solutions.

Now we plug in the initial values $x = 0$ and $y = 2$ and solve for the arbitrary constant, which we compute to be $\exp(2) - \log|4|/2.$ So the solution to the initial value problem is $$y = \log((1/2)\log|2x + 4| + \exp(2) - \log|4|/2).$$

You may reload this page to generate additional examples.


If you have any problems with this page, please contact bennett@ksu.edu.
©1994-2025 Andrew G. Bennett