5.4.d – Summary: Properties of Identity, Inverses, and Zero

Key Concepts

  • Identity Properties
    • Identity Property of Addition:
      For any real number aa: a+0=a(0)+a=aa+0=a(0)+a=a00 is the additive identity
    • Identity Property of Multiplication:
      For any real number aa:

      • a1=aa1=a
      • 1a=a1a=a
      • 11 is the multiplicative identity
  • Inverse Properties
    • Inverse Property of Addition: For any real number aa: a+(a)=0aa+(a)=0a is the additive inverse of aa
    • Inverse Property of Multiplication: For any real number aa: (a0)a1a=1(a0)a1a=1.   The multiplicative inverse of aa is 1a1a.
  • Properties of Zero
    • Multiplication by Zero: For any real number aa,
      a0=00a=0The product of any number and 0 is 0.a0=00a=0The product of any number and 0 is 0.
    • Division of Zero: For any real number aa,
      0a=00+a=0Zero divided by any real number, except itself, is zero.0a=00+a=0Zero divided by any real number, except itself, is zero.
    • Division by Zero: For any real number aa, 0a0a is undefined and a÷0a÷0 is undefined. Division by zero is undefined.

Glossary

Additive Identity
The additive identity is 00. When zero is added to any number, it does not change the value.
Additive Inverse
The opposite of a number is its additive inverse. The additive inverse of a is aa .
Multiplicative Identity
The multiplicative identity is 11. When one multiplies any number, it does not change the value.
Multiplicative Inverse
The reciprocal of a number is its multiplicative inverse. The multiplicative inverse of aa is 1a1a .