# Equations

There are two** sides** in an equation with an algebraic expression in each one.

Each monomial is a** term** of the equation.

“x” is called the** variable** or the **unknown**.

The **degree** of an equation is the biggest degree of its terms. If the degree is 1, we call it a **linear equation** and if the degree is 2 we call it a **quadratic equation**.

Examples:

· x^{2} – 3x + 1 = 5x -17 is a quadratic equation

· x + 5 – 3(x + 2) = 5x is a linear equation

Two equations are equivalent if they have exactly the same solutions.

3x = 6 is equivalent to x = 2

To **solve an equation** is to find the simplest equivalent equation that gives us the solution.

To obtain an equivalent equation we can do only two basic operations:

- Add or subtract the same expression in both sides of the equation.

- Multiply or divide by the same number (except zero) in both sides of the equality.

**Exercise**: Find the error

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