A term is a mathematical expression that consists of constants, variables, or a combination of both, and it is separated from other terms by addition or subtraction operators.

A constant term does not contain any variables.

A factor is a part of a term that is either a constant or a variable, or it can be a combination of both. Factors within a term are typically separated by multiplication or division operators.

The coefficient of a term is the numerical (non-variable) value that multiplies the variable(s) within that term. It represents the scaling or proportionality factor of the variable(s).

There are two types factors:

• $4$ is a constant factor
• $xy$ is a variable factor.

• A variable is a symbol or letter used to represent an unknown or changing quantity within an algebraic expression or equation.
• Variables can take on various values, and their values are not fixed.

$2$

1. Expression is a statement of values/quantity. Expression do not have an equal sign.
2. Equation is setting expressions to equals to them.

1. Dependent variable represents a quantity whose value depends on the independent variable
2. Independent variable is a variable that represents a quantity that is being manipulated in an experiment.

Mathematical expressions or statements that describe a relationship between two quantities, indicating that one quantity is greater than, less than, or not equal to another quantity.

• To maintain the relative order.
• For example, given $x = 5, y = 6$ we know that $x < y.$ When multiply both sides by $-1$, we get $x = -5, y=-6$. Without swapping the sign we get $-5 < -6$ and that is incorrect. We need to swap the inequality sign.