Let C* be the set of 2 ×2 matrices of the form
æ
ç
è
x
-y
y
x
ö
÷
ø
where x and y are real numbers and addition and multiplication are defined according to the usual rules for adding and multiplying matrices.

(a) Add and multiply the matrices
æ
ç
è
x
-y
y
x
ö
÷
ø
 and   æ
ç
è
u
-v
v
u
ö
÷
ø
.
(b) What are the identities and inverses for addition and multiplication?

(c) Consider also the subset R* for which y=0. Investigate the arithmetic of R* (addition, subtraction, multiplication, division, identities, inverses, distributive law) and compare it with the arithmetic of real numbers.

(d) Compare the arithemetic of C* with that of complex numbers.

(e) The matrix
æ
ç
è
-1
0
0
-1
ö
÷
ø

is equivalent to the real number -1. What is the matrix equivalent to
i =   __
Ö-1
 

in the set of complex numbers?