Exercise 14.4.1

Prove that M 1 = AΓL ( 1 , 𝔽 p 2 ) is solvable, and compute its order.

Answers

Proof. Recall that AGL ( 1 , 𝔽 p 2 ) 𝔽 p 𝔽 p , where ( 𝔽 p , + ) and ( 𝔽 p , × ) are cyclic, thus solvable, hence AGL ( 1 , 𝔽 p 2 ) is solvable by Theorem 8.1.4.

By Exercise 14.3.3(a), AGL ( 1 , 𝔽 p 2 ) has index 2 in AΓL ( 1 , 𝔽 p 2 ) , therefore AGL ( 1 , 𝔽 p 2 ) is a normal subgroup of AGL ( 1 , 𝔽 p 2 ) , and

AΓL ( 1 , 𝔽 p 2 ) AGL ( 1 , 𝔽 p 2 ) { 1 , 1 } .

The group { 1 , 1 } is cyclic, of prime order 2 , therefore is solvable, and AGL ( 1 , 𝔽 p 2 ) is solvable. The same Theorem 8.1.4 shows that M 1 = AΓL ( 1 , 𝔽 p 2 ) is solvable.

By Exercise 14.3.26,

| M 1 | = 2 p 2 ( p 2 1 ) .

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2022-07-19 00:00
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