What are variables in algebra?

In this lesson, we will learn:

• The parts of a math equation for all four operations: addition, subtraction, multiplication, division
• How to do basic algebra: solving for unknowns (variables) in equations
• How to write algebra equations from word sentences by using equation models to help

Notes:

• A math equation can be thought of as a mathematical sentence which needs terms, an operation and an answer

• An unknown is a value that we don't know in an equation yet; we need to solve the equation to find the unknown through guess-and-check (knowing that values must be equal on both sides of the equal sign)

• Algebra is a type of math where we will see BOTH numbers and letters (or symbols)!
• We use variables (letters or symbols) to represent unknown values:

• Equation models help identify all the terms when you're dealing with word sentences so that you can write an algebra equation

• i.e. "36 added to 41 equals $y$." $\,$→$\,$36 + 41 = $y$
• i.e. "15 less than $f$ equals 13." $\,$→$\,$$f$ - 15 = 13
• i.e. "2 times as many as 7 is $m$." $\,$→$\,$2 × 7 = $m$
• i.e. "$x$ is 3 times less than 15" $\,$→$\,$$x$ = 15 ÷ 13

• Keywords (key phrases) for each operation include:
• Addition: "added to", "more than", "increased by"
• Subtraction: "subtracted from", "less than", "decreased by"
• Multiplication: "multiplied by", "times", "times as many", "each", "groups"
• Division: "divided by", "times as many", "split into groups"