ALGEBRAIC EXPRESSIONS

Essentional Question

What is Algebraic Expressions and how do I solve them?

Vocabulary

Algebraic Expressions-an expression containing numbers, variables, and operations (eg, 3x + y or 5a – 4). Algebraic expressions do not contain equality or inequality symbols.

Variables-a symbol for a number we don't know yet.

Expressions-a mathematical term or a sum or difference of mathematical terms that may use numbers, variables, or both.

Equation-a statement that two numbers or expressions are equal

Variables

Usually we use letters such as n, t, or x for variables.

For example, we might say that s stands for the side-length of a square. We now treat s as if it were a number we could use. The perimeter of the square is given by 4 × s. The area of the square is given by s × s. When working with variables, it can be helpful to use a letter that will remind you of what the variable stands for: let n be the number of people in a movie theater; let t be the time it takes to travel somewhere; let d be the distance from my house to the park. 

Expressions

3 + 7 2 × y + 5 2 + 6 × (4 - 2) z + 3 × (8 - z)

Equations

Equations are useful for relating variables and numbers. Many word problems can easily be written down as equations with a little practice. Many simple rules exist for simplifying equations.

17 = 2 + 15 x = 7 7 = x t + 3 = 8 3 × n +12 = 100

Solving Expressions

To solve an expression for a given value for the variable, plug the value of the variable into the expression and simplify using the correct order of operations.

Question: If n = 125.17, what is the value of 256.39 - n?

Answer: Simply plug in the number for n and solve the expression.256.39 - n = 256.39 - 125.17 = 131.22

Your Turn to Try It!!

If n = 81, what is the value of n ÷ 9? If n = 590, what is the value of n - 352? If n = 91, what is the value of 186 + n?

Summarizer

Tell a partner : How you solve an Algebraic Expression?

Homework

Algebraic Expression Worksheet