Solve the following differential equation ;

y' = 2y'x + 1/y

1 answer

To solve the differential equation

\[ y' = 2y'x + \frac{1}{y}, \]

we start by rewriting it in a standard form. First, let's express \(y'\) as a function of \(y\) and \(x\). We can rearrange the equation as follows:

\[ y' - 2yx' = \frac{1}{y}. \]

This is fairly complicated given the \(y'\) terms, so let's try a separation of variables approach.

Rearranging the differential equation gives us:

\[ y' (1 - 2x) = \frac{1}{y}. \]

Assuming that \(1 - 2x \neq 0\), we can separate variables:

\[ y' = \frac{1}{y(1-2x)}. \]

Now write \(y' = \frac{dy}{dx}\):

\[ \frac{dy}{dx} = \frac{1}{y(1 - 2x)}. \]

Now we can separate the variables:

\[ y , dy = \frac{1}{(1-2x)} , dx. \]

Now integrate both sides:

\[ \int y , dy = \int \frac{1}{1-2x} , dx. \]

The integrals are:

\[ \frac{y^2}{2} = -\frac{1}{2} \ln |1 - 2x| + C, \]

where \(C\) is a constant of integration.

Multiplying both sides by 2 gives us:

\[ y^2 = -\ln |1 - 2x| + D, \]

where \(D = 2C\).

So the general solution to the differential equation can be expressed as:

\[ y^2 = D - \ln |1 - 2x|. \]

This represents the relationship between \(y\) and \(x\) implicit in the original differential equation.

To express it in a more recognizable form, we can also write:

\[ y = \sqrt{D - \ln |1 - 2x|}. \]

This is the general solution to the given differential equation.