# Basic terminology

Put content here.**Definition:** A linear equation is an equation that can be written in the form
⏎
$$a_1 x_1 + a_2 x_2 + \cdots + a_n x_n = b$$
⏎
where $x_1, x_2, \ldots, x_n$ are variables (unknowns), $a_1, a_2, \ldots, a_n$ are constants called **coefficients**, and $b$ is a constant called the **right-hand side** or **constant term**.
⏎
The key property of a linear equation is that each variable appears only to the first power and is not multiplied by another variable, composed with a nonlinear function, or raised to any power other than 1.
⏎
**Examples:**
- $2x + 3y = 6$ is linear
- $x_1 - 4x_2 + x_3 = 0$ is linear
- $x^2 + y = 1$ is **not** linear (variable squared)
- $xy = 3$ is **not** linear (variables multiplied together)

# Parents

* Linear systems of equations