ALGEBRA

# Expressions

An **expression** is a mixture of numbers, letters and symbols (+, - , · …) that doesn’t include the = symbol.

3 x - 5 (a + b)^{2}

To **substitute** in an expression is to put numbers in place of letters.

The **value** of an expression is the answer you get after substituting numbers for letters:

the value of 3 x + 5 is 14 if x = 3

**Exercise**: calculate the value after substituting x = 5 in these expressions:

Solutions: a) 1; b) 16; c) 5

Licensed under the Creative Commons Attribution Non-commercial Share Alike 3.0 License