G is a group of order 51. Then which one of the following statements i...
Given G is a group of order 51.
i.e. o(G) = 51 = 3 x 17
All subgroup of group is cyclic.
The subgroups are of odd order so each element will have its inverse different from itself.
So, If G is abelian then there exists no proper subgroup H of G such that product of all elements of H is identity is false.
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G is a group of order 51. Then which one of the following statements i...
Statement: G is a group of order 51.
False Statement: If G is abelian then there exists no subgroup H of G such that the product of all elements of H is the identity.
To prove this false statement, let's consider the given group G of order 51.
Proof:
1. All proper subgroups of G are cyclic:
This statement is true for any group of prime order. Since 51 is not a prime number, G cannot have all proper subgroups as cyclic. Hence, option (a) is true.
2. If G has only one subgroup of order 3 and only one subgroup of order 17, then G is cyclic:
This statement is true according to the Fundamental Theorem of Cyclic Groups. If G has only one subgroup of order 3 and only one subgroup of order 17, then G is cyclic. Therefore, option (b) is true.
3. G must have an element of order 17:
This statement is true according to Cauchy's Theorem. Since 17 is a prime divisor of the order of G, G must have an element of order 17. Hence, option (c) is true.
4. If G is abelian then there exists no subgroup H of G such that the product of all elements of H is the identity:
This statement is false. Let's prove it by contradiction.
Assume that G is an abelian group and there exists a subgroup H of G such that the product of all elements of H is the identity.
Since G is abelian, the product of all elements of H can be written as:
(1) h1 * h2 * h3 * ... * hk = e, where e is the identity element of G.
Since H is a subgroup of G, it is closed under the group operation. Therefore, the product of any two elements in H will also be in H.
Now, consider the element h1 in H. Since H is closed under the group operation, h1 * h1 = h2 is also in H.
Similarly, h2 * h2 = h3, and so on.
Continuing this process, we can deduce that h1 * h1 * h1 * ... * h1 = hk is also in H.
But hk is the identity element of G, which means H contains the identity element.
Therefore, the product of all elements of H is the identity element of G.
Hence, the false statement is option (d).
In conclusion, the false statement is option (d).