1. Algebraic Expressions
Lesson 1-2
Algebraic Expressions

2. Variable – a symbol, usually a letter, that represents one or more numbers.
Algebraic expression (variable expression) – an expression that contains one or more variables.
Evaluate – when you substitute numbers in for variables and follow the order of operations to solve the problem.

3. Evaluate a – 2b + ab for a = 3 and b = -1

4. Term – part of an algebraic expression that is being added
Term – part of an algebraic expression that is being added. It can be a number, a variable, or the product of a number and one or more variables.
Coefficient – numerical factor in a term
Like terms have the same variables raised to the same power.

5. 3x2 and -7x2 are like terms
5x2y3 and 9x3y2 are not like terms
To combine like terms add or subtract their coefficients

6. Definition of Subtraction
a – b = a + (-b)
Definition of Division
a / b = a ∙ 1/b , b ≠ 0
Distributive Prop. for Subtraction
a(b – c) = ab – ac
Mult. By 0
0 ∙ a = 0
Mult. By -1
–1 ∙ a = –a
Opposite of a sum
–(a + b) = –a + (–b)
Opposite of a difference
–(a – b) = b – a
Opposite of a product
–(ab) = –a ∙ b = a ∙ (–b)
Opposite of an opposite
–(–a) = a

7. Examples
Evaluate each expression for c = -3 and d = 5
c(3 – d) – c2
Combine like terms
2x2 + 5x – 4x2 + x – x2

9. Assignment: 2 – 46ab, even 68-70 on pg 15-16