An expression is a mathematical sentence that can contain constants, variables (like x or y), and operators like +, –, ×, ÷
5x − 8 + 5y
term term term expression
A numerical expression contains only numbers and operations.
An algebraic expression may contain numbers, operations, and one or more variables.
Working with expressions
Something to think about …
The algebraic expression for the momentum of a moving object is mass × velocity , or mv, where mass is in kg and velocity is in metres per second ( m / s ) .
A balloon has a mass of 500 grams and a velocity of 2 m / s going in a particular direction.
A runner going in the same direction has a mass of 70 kg and a velocity of 4 m / s
Will the balloon or the runner have the greatest momentum?
20.1 Expressions
By the end of this section you should: ● understand what an expression is ● be able to write expressions from word problems