Numbers, symbols, and operators (such as + and ×) grouped together to show the value of something.

Examples:
• 2 + 3 is an expression
• 3 − x/2 is also an expression

Note: an expression does not have an equals sign. In fact none of these: = ≠ < > ≤ ≥

What is an Equation?

An equation says that two things are equal. It will have an equals sign “=” like this:

That equation says: what is on the left (x + 2) is equal to what is on the right (6)

So an equation is like a statement “this equals that“

Here we have an equation that says 4x − 7 equals 5, and all its parts:

A Variable is a symbol for a number we don’t know yet. It is usually a letter like x or y.

A number on its own is called a Constant.

A Coefficient is a number used to multiply a variable (4x means 4 times x, so 4 is a coefficient)

Variables on their own (without a number next to them) actually have a coefficient of 1 (x is really 1x)

Sometimes a coefficient is a letter like a or b instead of a number:

Example: ax² + bx + c

• x is a variable
• a and b are coefficients
• c is a constant

An Operator is a symbol (such as +, ×, etc) that shows an operation (ie we want to do something with the values).

A Term is either a single number or a variable, or numbers and variables multiplied together.

An Expression is a group of terms (the terms are separated by + or − signs)

Exponents

The exponent (such as the 2 in x²) says how many times to use the value in a multiplication.