The center of GL(n, F). Let F be a field (the rationals, the reals, the complexes, or Z/pZ). Show that Z(GL(n, F)), the center of the general linear group, is {AIn XE F}, the set of matrices that are constant multiples of the identity matrix. You may find the following steps helpful: Step 1: For 1s i, j < n, let E be then x n matrix that has a one in the (i, j) entry and zeros elsewhere. Show that B; i elementary matrix and hence an element of GL(n, F). Step 2: Assume that A E Z(GL(n, F)). Show that ABj = BijA implies that AEj = Ei,jA. Step 3: If A E Z(GL(n, F)), by comparing AEij with EijA, conclude that A = AI,n for some X E F. = In + Eij is an %3D

Elements Of Modern Algebra
8th Edition
ISBN:9781285463230
Author:Gilbert, Linda, Jimmie
Publisher:Gilbert, Linda, Jimmie
Chapter8: Polynomials
Section8.6: Algebraic Extensions Of A Field
Problem 7E
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Show that the center of the General Linear Group is { \lambda * I_n | \lambda is in a rational / real / complex / modulo field }, the set of matrices that are constant multiples of the identity matrix.

1.5.6. The center of GL(n, F). Let F be a field (the rationals, the reals, the
complexes, or Z/pZ). Show that Z(GL(n, F)), the center of the general
linear group, is {AIn X E F}, the set of matrices that are constant
multiples of the identity matrix. You may find the following steps helpful:
Step 1: For 1< i,j < n, let Eii be the n x n matrix that has a one
in the (i, j) entry and zeros elsewhere. Show that Bj = In + Eij is an
elementary matrix and hence an element of GL(n, F).
Step 2: Assume that A E Z(GL(n, F). Show that ABj = B¡jA implies
that AEj = EijA.
Step 3: If A E Z(GL(n, F)), by comparing AEij with Eij A, conclude
that A = XIn for some E F.
Transcribed Image Text:1.5.6. The center of GL(n, F). Let F be a field (the rationals, the reals, the complexes, or Z/pZ). Show that Z(GL(n, F)), the center of the general linear group, is {AIn X E F}, the set of matrices that are constant multiples of the identity matrix. You may find the following steps helpful: Step 1: For 1< i,j < n, let Eii be the n x n matrix that has a one in the (i, j) entry and zeros elsewhere. Show that Bj = In + Eij is an elementary matrix and hence an element of GL(n, F). Step 2: Assume that A E Z(GL(n, F). Show that ABj = B¡jA implies that AEj = EijA. Step 3: If A E Z(GL(n, F)), by comparing AEij with Eij A, conclude that A = XIn for some E F.
Expert Solution
Step 1

Given GLn,F be the general linear group of all invertible matrices whose entries belongs to the field F.

Let ZGLn,F be the center of group GLn,F.

Since identity matrix belongs to center of group GLn,F, therefore ZGLn,F is a non empty set.

For 1i,jn, let Ei,j be a n×n matrix whose i,j entry is 1 and else entries are zero.

Let In be identity matrix of order n×n.

Now consider In+Ei,j.

Since In is an identity matrix, therefore if ij, then the all diagonal entries of In+Ei,j will be one and i,j entry one and elsewhere zero.

If i=j, then i,j entry of In+Ei,j is 2 and all other diagonal entries will be one and else where zero. Therefore:

In+Ei,j=1ij2i=j

Therefore  the matrix In+Ei,j is an invertible matrix and hence In+Ei,jGLn,F.

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