1. **State the problem:** Solve the differential equation $$\frac{dy}{dx} = 2y$$ and find the general solution.
2. **Use the method of separation of variables:** Rewrite the equation as $$\frac{dy}{y} = 2 \, dx$$.
3. **Integrate both sides:**
$$\int \frac{1}{y} \, dy = \int 2 \, dx$$
which gives
$$\ln|y| = 2x + C$$
where $C$ is the constant of integration.
4. **Solve for $y$:**
Exponentiate both sides:
$$y = e^{2x + C} = e^C e^{2x}$$
Let $C_1 = e^C$, so
$$y = C_1 e^{2x}$$
This is the general solution.
5. **Find the particular solution given $y(2) = 4$:**
Substitute $x=2$ and $y=4$:
$$4 = C_1 e^{2 \cdot 2} = C_1 e^4$$
Solve for $C_1$:
$$C_1 = \frac{4}{e^4} = 4 e^{-4}$$
6. **Write the particular solution:**
$$y = 4 e^{-4} e^{2x} = 4 e^{2x - 4}$$
**Note:** The expression $y = \sqrt{2x^2 + 4}$ is unrelated to the solution of this differential equation.
Diff Eq Solution D2001F
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