The arithmetic operations with real numbers are governed by the following axioms:
(1) Closure Axiom of Addition / Multiplication
For real numbers a and b,
a + b is a unique real number
ab is a unique real number
(2) Commutative Axiom of Addition / Multiplication
For real numbers a and b,
a + b = b + a
ab = ba
(3) Associative Axiom of Addition / Multiplication
For real numbers a, b and c,
( a + b ) + c = a + ( b + c )
(ab)c = a(bc)
(4) Identity Axiom of Addition
For any real number a,
a + 0 = 0 + a = a
(5) Identity Axiom of Multiplication
For any real number a,
a(1) = 1(a) = a
(6) Additive Inverse Axiom
For any real number a, there exists a unique real number -a such that
a + (-a) = -a + a = 0
The number -a is known as the additive inverse of a.
(7) Multiplicative Inverse Axiom
For any nonzero real number a, there exists a unique real number
( 1 / a ) such that
a ( 1 / a ) = ( 1 / a ) a = 1
The number ( 1 / a ) is known as the multiplicative inverse or reciprocal of a, where a ¹ 0.
(8) Distributive Axiom
For any real numbers a, b, and c,
a ( b + c ) = ab + ac
a ( b - c ) = ab - ac
( a + b) c = ac + bc
( a - b) c = ac - bc