Mathematics Grade 9 15 min

Properties of addition and multiplication

Properties of addition and multiplication

Tutorial Preview

1

Introduction & Learning Objectives

Learning Objectives Identify the commutative, associative, and distributive properties in algebraic expressions. Apply the properties of addition and multiplication to simplify polynomial and radical expressions. Justify each step in simplifying an algebraic expression by naming the property used. Differentiate between the commutative and associative properties. Use the identity and inverse properties to solve equations and simplify expressions. Correctly apply the distributive property to expressions involving negative signs and multiple variables. Ever noticed that when you're shopping, it doesn't matter if you buy the apples then the bananas, or the bananas then the apples? The total cost is the same! 🛒 These 'rules' also apply to algebra. This tutor...
2

Key Concepts & Vocabulary

TermDefinitionExample Commutative PropertyThis property states that the order in which you add or multiply two numbers (or terms) does not change the result.For addition: 5x + 3 = 3 + 5x. For multiplication: (2y) * 4 = 4 * (2y). Associative PropertyThis property states that the way you group three or more numbers (or terms) when adding or multiplying does not change the result. The order stays the same, but the parentheses move.For addition: (x^2 + 2x) + 5 = x^2 + (2x + 5). For multiplication: (3 * 4y) * z = 3 * (4y * z). Distributive PropertyThis property allows you to multiply a sum by multiplying each addend separately and then adding the products. It's the key to expanding expressions with parentheses.5(x - 3) becomes 5 * x - 5 * 3, which simplifies to 5x - 15. Identity PropertyT...
3

Core Formulas

Commutative Properties For any real numbers a and b: a + b = b + a and a * b = b * a Use this to reorder terms in an expression, often to group like terms together before combining them. Associative Properties For any real numbers a, b, and c: (a + b) + c = a + (b + c) and (a * b) * c = a * (b * c) Use this to regroup terms. This is especially useful in multiplication to make calculations easier, like in (2x * 50) * 7. Distributive Property For any real numbers a, b, and c: a(b + c) = ab + ac Use this to eliminate parentheses by 'distributing' the factor outside to every term inside. This is fundamental for multiplying polynomials.

4 more steps in this tutorial

Sign up free to access the complete tutorial with worked examples and practice.

Sign Up Free to Continue

Sample Practice Questions

Challenging
Which property is the fundamental reason that 'combining like terms' is a valid mathematical operation, as in 9x^2 + 5x^2 = 14x^2?
A.Commutative Property of Addition
B.Distributive Property
C.Associative Property of Addition
D.Multiplicative Identity Property
Challenging
Consider the equation 5(x - 2) + 10 = 15. A student solves it with the following steps: Step 1: 5x - 10 + 10 = 15 Step 2: 5x + 0 = 15 Step 3: 5x = 15 Which properties justify the transition from Step 2 to Step 3?
A.Additive Inverse and Additive Identity
B.Multiplicative Inverse and Multiplicative Identity
C.Additive Identity Property
D.Additive Inverse Property
Challenging
Let a new operation ★ be defined as a ★ b = 2a + b^2. Which statement is true about this operation?
A.★ is both Commutative and Associative.
B.★ is Commutative but not Associative.
C.★ is Associative but not Commutative.
D.★ is neither Commutative nor Associative.

Want to practice and check your answers?

Sign up to access all questions with instant feedback, explanations, and progress tracking.

Start Practicing Free

More from Properties

Ready to find your learning gaps?

Take a free diagnostic test and get a personalized learning plan in minutes.