Memo

Properties of Real Numbers

Real numbers have certain properties when it comes to operations, identities, and equalities.
Operations
Name Property
Distributive Property a * (a+c) = a * b + a * c
Commutative Property of Addition a + b = b + a
Commutative Property of Multiplication a * b = b* a
Associative Property of Addition (a+b)+c = a + (b+c)
Associative Property of Multiplication (a* b)* c = a * (b * c)
Identities
Name Property
Additive Identity a+0 = a
Multiplicative Identity a*1=a
Equalities
Name Property
Addition Property of Equality If a=b, then a+c=b+c
Subtraction Property of Equality  If a=b, then a-c=b-c
Multiplication Property of Equality If a=b, then a* c=b* c
Division Property of Equality If a=b, then a/c=b/c
Reflexive Property of Equality Any real number is equal to itself
Symmetric Property of Equality If a=b, then b=a
Transitive Property of Equality If a=b and b=c, then a=c
Closure Property of Real Numbers
∀ a,b ∈ R ⇒ a + b ∈ R Closed Under Addition
∀ a,b ∈ R ⇒ a - b ∈ R Closed Under Subtraction
∀ a,b ∈ R ⇒ a * b ∈ R Closed Under Multiplication
∀ a,b ∈ R ⇒ a ÷ b /∈ R Not Closed Under Division
Exercises
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