# Expressions with Letters

## Overview

In order to write and solve expressions involving letters, we need to first understand

variables, terms, and coefficients.

VARIABLES | TERMS |
---|---|

A variable is a symbol that’s used to represent an unknown number |
Terms are single numbers or variables. They can also be a set of numbers and variables that are multiplied together |

3 + 2x = 9 |
3 + 2x = 9 |

x is the variable |
There are 3 terms: (3, 2x, and 9) |

COEFFICIENTS |
---|

Coefficients are numbers placed before a variable when multiplying |

3 + 2x = 9 |

2 is a coefficient |

Let’s try using some of the new vocabulary.

The following expression has____ coefficient(s), _____ term(s) and ____variable(s).

**2x – 3**

[ANSWER] 1 coefficient, 2 terms, and 1 variable

Now that we understand the vocabulary, we can begin to solve expressions involving variables.

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Which expression has exactly **2** variables?

**A.** 2(2 + 3) – 3x**B. ** 2x + y**C.** 2x + 2 = 10

B

Variables are symbols used to represent unknown numbers. **x** and **y** are

variables in this expression

Which expression represents the sum of **3** terms?**A.** 3b + c**B.** (3 + b) + c**C.** 3 + b + c

C

Terms are single numbers or variables. They can also be a set of numbers of

variables multiplied together. **3**, **b**, and **c** are terms in this expression.

What is the coefficient in the expression **7z + 3**?**A.** 7**B.** z**C.** 3

A

Coefficients are numbers placed before variables when multiplying. **7** is the

coefficient in this expression.

How many terms are in the expression **xy + cd**?**A.** 1**B.** 2**C.** 4

B

Terms are single numbers or variables. They can also be a set of numbers of

variables multiplied together. **xy** is one term. **cd** is another term.

Write an expression to represent** 5** times **y.**

5 x y or 5y

The word “times” signals multiplication.

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