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Differential Equations Practice Sheet
Introduction
Differential equations are equations involving derivatives. Derivatives are used to measure the rate of change of a function with respect to one or more of its variables. Differential equations are used to describe the behavior of systems in many areas such as physics, engineering, and economics.
Differential Equations
A differential equation is an equation that relates a function and its derivatives. It can be written in the form of:
$$F(x,y,y',y'',...)=0$$
where $F$ is a function of $x$, $y$, $y'$, $y''$, and so on.
Types of Differential Equations
There are two main types of differential equations:
Ordinary Differential Equations (ODEs): These equations involve one independent variable, typically denoted by $x$.
Partial Differential Equations (PDEs): These equations involve two or more independent variables, typically denoted by $x$ and $y$.
Examples
ODE: $$\frac{dy}{dx} = x2 + y2$$
PDE: $$\frac{\partial u}{\partial t} = c2\frac{\partial2 u}{\partial x2}$$
Practice Problems
Solve the following ODE: $$\frac{dy}{dx} = x + y$$
Solve the following PDE: $$\frac{\partial u}{\partial t} = \frac{\partial2 u}{\partial x2}$$
Find the general solution to the following ODE: $$\frac{dy}{dx} = x2 + y2$$
Find the general solution to the following PDE: $$\frac{\partial u}{\partial t} = c2\frac{\partial2 u}{\partial x2}$$
Find the particular solution to the following ODE with the initial condition $y(0) = 1$: $$\frac{dy}{dx} = x + y$$
Find the particular solution to the following PDE with the initial condition $u(x,0) = f(x)$: $$\frac{\partial u}{\partial t} = c2\frac{\partial2 u}{\partial x2}$$
Find the solution to the following system of ODEs:
$$\frac{dx}{dt} = x + y$$
$$\frac{dy}{dt} = x - y$$
- Find the solution to the following system of PDEs:
$$\frac{\partial u}{\partial t} = c2\frac{\partial2 u}{\partial x2}$$
$$\frac{\partial v}{\partial t} = c2\frac{\partial2 v}{\partial x2}$$
- Find the solution to the following system of ODEs with the initial conditions $x(0) = 0$, $y(0) = 1$:
$$\frac{dx}{dt} = x + y$$
$$\frac{dy}{dt} = x - y$$
- Find the solution to the following system of PDEs with the initial conditions $u(x,0) = f(x)$, $v(x,0) = g(x)$:
$$\frac{\partial u}{\partial t} = c2\frac{\partial2 u}{\partial x2}$$
$$\frac{\partial v}{\partial t} = c2\frac{\partial2 v}{\partial x2}$$