AMC 125: Lesson, November 19, 2008

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Topic: Ring Properties

pp. 677 - 679, Grimaldi

Definition 3: Multiplicative Inverse

Let R be a ring with unity u.

If a ∈R and there exists b∈R such that ab=ba=u,

then b is called a multiplicative inverse of a and a is called a unit of R.

(The element b is also a unit of R.)

Definition 4: Let R be a commutative ring with unity. Then

a) R is called an integral domain if R has no proper divisors of zero

b) R is called a field if every nonzero element of R is a unit.


Group Activity:

Study Example 14.6 on page 678

Graded Activity (To be submitted)

Answer completely problem no. 9 on pages 678 - 679.

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