# Math Help - definition

1. ## definition

hi

may i know what it means by R ^x where R= real numbers? and what does GL (subscript 2) (R) means?

thanks

2. Originally Posted by alexandrabel90
hi

may i know what it means by R ^x where R= real numbers? and what does GL (subscript 2) (R) means?

thanks

For any field (or even commutative ring) $R\,,\,\,R^{*}:=R\setminus \{0\}\,\,\,(or\,\,\,R^{*}=$ the set of all units in the ring R) , and $GL_2(R)=$ the set of all invertible 2 x 2 matrices with elements in R (or the set of all R-automorphism of the R-module R x R)

Tonio

3. then what is the different between GL (subscript 2) (R) and SL(subscript 2) (R)?

THANKS!!!