Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

find the order of GL(2,R), where R is the group of integers modulo 3. As a hint,

ID: 2961488 • Letter: F

Question

find the order of GL(2,R), where R is the group of integers modulo 3.  As a hint, it is helpful to consider the cases where a matrix has 0,1,2,3, or 4 zeros separately.  Afterwards, spend some time thinking about other cases for R (integers mod 4, mod 5, mod p, etc.)  The total number of possible matrices increases very quickly.  Generalizing for any modulus (prime or composite) is probably too difficult, but I would like each of you to write down any observations that you made which would help in narrowing down the possibilities for the order of the group.

Explanation / Answer

integer modulo 3 are 0,1,2 so for each of the four elements there is four options. so order of GL(2,R)=3^4=81 when R-integers mod 3..

in general when R is integers mod n then order of GL(2,R) is n^4