Let G be the set of matrices over R.

Show that G is isomorphic to .

I know GL2R represents the matrices

1 0

0 1

-1 0

0 1

1 0

0 -1

-1 0

0 -1

But how can I show it is isomorphic to ?

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- October 28th 2009, 11:26 AMelninioShow GL_2(R) is isomorphic to Z_2 x Z_2
Let G be the set of matrices over R.

Show that G is isomorphic to .

I know GL2R represents the matrices

1 0

0 1

-1 0

0 1

1 0

0 -1

-1 0

0 -1

But how can I show it is isomorphic to ? - October 28th 2009, 11:40 AMtonio

Something doesn't fit in here: if R is the real numbers, then denotes the group of all invertible 2 x 2 matrices with real entries and this is an infinite group, so it cannot possibly be isomorphic with the Klein group, a group of order 4.

Please do detail what you mean by

Tonio - October 28th 2009, 11:44 AMelninio
Looks like i've made a mistake in the translation of the question. I misused notation.

The questions direct translation is:

Let G be the following set of matrices over R:

1 0

0 1

-1 0

0 1

1 0

0 -1

-1 0

0 -1

Show that G is isomorphic to Z_2 x Z_2.

This makes more sense, right? - October 28th 2009, 11:46 AMclic-clac
There are only two groups (up to isomorphism) of order 4: which is cyclic, and whose non trivial elements are of order 2.

So showing that the square of any matrix in your group is the identity is sufficient to prove that it is isomorphic to