If a group has 5 element of order 2,then if it is abelian then is it p...
Introduction:In this question, we are given a group that has 5 elements of order 2, and we need to determine if it is possible for this group to be abelian. To answer this question, we will first define what it means for a group to be abelian and then explore the properties of a group with 5 elements of order 2.
Abelian Groups:An abelian group, also known as a commutative group, is a group where the order of the elements does not matter. In other words, for any two elements a and b in the group, ab = ba. This property is named after the mathematician Niels Henrik Abel.
Properties of a Group with 5 Elements of Order 2:Let's assume that our group G has 5 elements of order 2 - let's call them a, b, c, d, and e. Since the order of an element is the smallest positive integer n such that a^n = e (the identity element), we have the following properties for our group:
- a^2 = e
- b^2 = e
- c^2 = e
- d^2 = e
- e^2 = e
Proof by Contradiction:To determine if our group is abelian, we need to verify if ab = ba for all pairs of elements a and b in the group. We will use a proof by contradiction to show that if our group has 5 elements of order 2, it cannot be abelian.
Assume that our group G is abelian, and let's consider the pair ab. Since a and b both have order 2, we have the following possibilities:
- If a = b, then ab = aa = a^2 = e.
- If a ≠ b, then ab ≠ ba, as this would contradict the abelian property.
Now, let's consider a pair of different elements, say a and b. If we assume that ab = ba, then we can write it as a multiplication table:
* |
a |
b |
c |
d |
e |
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a |
e |
* |
* |
* |
* |
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b |
* |
e |
* |
* |
* |
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c |
* |
* |
e |
* |
* |
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d |
* |
* |
* |
e |
* |
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e |
* |
* |
* |
* |
e |
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From the table, we can see that ab = ba only for the pair (a,a), which means that the only way for our group to be abelian is if a = b = c = d = e. However, this contradicts the given condition that the group has 5 elements of order 2.
Conclusion:Therefore, it is