I don't understand what it means when they say write an expression with a variable. could you please write an example for me? Thank you.

Expert Answers
Matthew Fonda eNotes educator| Certified Educator

An expression can be thought of as just a bunch of mathematical symbols, put together in a way that makes sense according to the rules of mathematics. For example, the following are expressions:

5 + 10

8 * (11 + 4) / 3 - 5


As stated above, an expression must follow the rules of mathematics. For example, the following is NOT an expression: 4 *+--54(

A variable can be thought of as something that holds the place of something else. Variables will commonly be denoted by the letters x, y.

An expression with a variable is just an expression that has a variable in it. The following are examples of expressions with variables:

4x - 8y

8x^2 + 3x - 5

x / y

taylormath eNotes educator| Certified Educator

Common textbook problems ask students to write an algebraic expression to resemble a verbal expression.  For instance, "eight less than a number" translates to n-8. Algebraic expressions are a concise way to write lengthy verbal expressions.  The following are a few more examples.

The sum of seven times a number and 3.

7x + 3

The product of two and the sum of a number and 9.

2(x + 9)

Twelve more than the quotient of a number and nine.

x/9 + 12

The quotient of a number and the sum of twelve and nine.

x/(12 + 9)

When writing an algebraic expression, make sure to read the verbal statement carefully.  Most mistakes are caused by trying to get the problems done quickly.