- #1
gottfried
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Homework Statement
If a.a=a for all elements of R, prove R is commutative.
The Attempt at a Solution
(a+b)2=a+b=a2+ba+ab+b2=a+ba+ab+b
Then -ba=ab
Any suggestions of how to show that -b=b?
In mathematics, a group is commutative if its binary operation, typically denoted as "x * y" or "xy", satisfies the commutative law "x * y = y * x" for all elements x and y in the group. This means that the order in which the elements are combined does not affect the result.
The equation a.a = a, also known as the idempotent law, is a property of commutative groups. It states that any element multiplied by itself will always equal that same element. This property, along with other group axioms, can be used to prove that the group is commutative.
No, a group cannot be commutative if it does not follow the equation a.a = a. This equation is a fundamental property of commutative groups and if it is not satisfied, the group is not commutative.
Some examples of commutative groups include the group of integers under addition, the group of real numbers under addition, and the group of positive real numbers under multiplication. These groups all satisfy the commutative law and are therefore commutative.
Proving that a group is commutative is important in mathematics because it allows us to simplify calculations and make generalizations about the behavior of a group. Commutative groups have special properties that can be used to solve problems and make predictions in various fields of mathematics, such as algebra, geometry, and number theory.