# 2.S: Introduction to the Language of Algebra (Summary)

### Key Terms

coefficient | The constant that multiplies the variable(s) in a term. |

composite number | A composite number is a counting number that is not prime. |

divisibility | If a number m is a multiple of n, then we say that m is divisible by n. |

equation | An equation is made up of two expressions connected by an equal sign. |

evaluate | To evaluate an algebraic expression means to find the value of the expression when the variable is replaced by a given number. |

expression | An expression is a number, a variable, or a combination of numbers and variables and operation symbols. |

least common multiple (LCM) | The smallest number that is a multiple of two numbers. |

like terms | Terms that are either constants or have the same variables with the same exponents. |

multiple of a number | A number is a multiple of n if it is the product of a counting number and n. |

prime factorization | The product of prime numbers that equals the number. |

prime number | A counting number greater than 1 whose only factors are 1 and itself. |

solution of an equation | A value of a variable that makes a true statement when substituted into the equation. The process of finding the solution to an equation is called solving the equation. |

term | A constant or the product of a constant and one or more variables. |

### Key Concepts

#### 2.1 - Use the Language of Algebra

Operation | Notation | Say: | The result is… |
---|---|---|---|

Addition | a + b | a plus b | The sum of a and b |

Multiplication | a • b, (a)(b), (a)b, a(b) | a times b | The product of a and b |

Subtraction | a - b | a minus b | The difference of a and b |

Division | a ÷ b, a / b, \(\frac{a}{b}\), \(b \overline{)a}\) | a divided by b | The quotient of a and b |

**Equality Symbol**- a = b is read as a is equal to b
- The symbol = is called the equal sign.

**Inequality**- a < b is read a is less than b
- a is to the left of b on the number line:
- a > b is read a is greater than b
- a is to the right of b on the number line:

#### Table 2.77

Algebraic Notation | Say |
---|---|

a = b | a is equal to b |

a ≠ b | a is not equal to b |

a < b | a is less than b |

a > b | a is greater than b |

a ≤ b | a is less than or equal to b |

a ≥ b | a is greater than or equal to b |

**Exponential Notation**- For any expression a n is a factor multiplied by itself n times, if n is a positive integer.
- a
^{n}means multiply n factors of a - The expression of a
^{n}is read a to the n^{th}power

**Order of Operations**: When simplifying mathematical expressions perform the operations in the following order:

- Parentheses and other Grouping Symbols: Simplify all expressions inside the parentheses or other grouping symbols, working on the innermost parentheses first.
- Exponents: Simplify all expressions with exponents.
- Multiplication and Division: Perform all multiplication and division in order from left to right. These operations have equal priority.
- Addition and Subtraction: Perform all addition and subtraction in order from left to right. These operations have equal priority.

#### 2.2 - Evaluate, Simplify, and Translate Expressions

**Combine like terms**.

- Identify like terms.
- Rearrange the expression so like terms are together.
- Add the coefficients of the like terms

#### 2.3 - Solving Equations Using the Subtraction and Addition Properties of Equality

**Determine whether a number is a solution to an equation.**

- Substitute the number for the variable in the equation.
- Simplify the expressions on both sides of the equation.
- Determine whether the resulting equation is true. If it is true, the number is a solution. If it is not true, the number is not a solution.

**Subtraction Property of Equality**- For any numbers a, b, and c, if a = b, then a - c = b - c.

- Solve an equation using the Subtraction Property of Equality.

- Use the Subtraction Property of Equality to isolate the variable.
- Simplify the expressions on both sides of the equation.
- Check the solution.

**Addition Property of Equality**- For any numbers a, b, and c, if a = b, then a + c = b + c.

- Solve an equation using the Addition Property of Equality.

- Use the Addition Property of Equality to isolate the variable.
- Simplify the expressions on both sides of the equation.
- Check the solution.

#### 2.4 - Find Multiples and Factors

Divisibility Tests | |
---|---|

A number is divisible by | |

2 | if the last digit is 0, 2, 4, 6, or 8 |

3 | if the sum of the digits is divisible by 3 |

5 | if the last digit is 5 or 0 |

6 | if divisible by both 2 and 3 |

10 | if the last digit is 0 |

**Factors:**If a • b = m, then a and b are factors of m, and m is the product of a and b.**Find all the factors of a counting number.**

- Divide the number by each of the counting numbers, in order, until the quotient is smaller than the divisor.
- If the quotient is a counting number, the divisor and quotient are a pair of factors.
- If the quotient is not a counting number, the divisor is not a factor.

- List all the factor pairs.
- Write all the factors in order from smallest to largest.

**Determine if a number is prime**.

- Test each of the primes, in order, to see if it is a factor of the number.
- Start with 2 and stop when the quotient is smaller than the divisor or when a prime factor is found.
- If the number has a prime factor, then it is a composite number. If it has no prime factors, then the number is prime.

#### 2.5 - Prime Factorization and the Least Common Multiple

**Find the prime factorization of a composite number using the tree method**.

- Find any factor pair of the given number, and use these numbers to create two branches.
- If a factor is prime, that branch is complete. Circle the prime.
- If a factor is not prime, write it as the product of a factor pair and continue the process.
- Write the composite number as the product of all the circled primes.

**Find the prime factorization of a composite number using the ladder method**.

- Divide the number by the smallest prime.
- Continue dividing by that prime until it no longer divides evenly.
- Divide by the next prime until it no longer divides evenly.
- Continue until the quotient is a prime.
- Write the composite number as the product of all the primes on the sides and top of the ladder.

**Find the LCM using the prime factors method**.

- Find the prime factorization of each number.
- Write each number as a product of primes, matching primes vertically when possible.
- Bring down the primes in each column.
- Multiply the factors to get the LCM.