 #1
 214
 0
Homework Statement
*attached
Homework Equations
The Attempt at a Solution
Let a,b ∈ H. Then (∀x ∈ S)(a*x = x*a) and (∀x ∈ S)(b*x = x*b). It is easy to see, then, that a*b = b*a. Now let c ∈ S. Then (a*b)*c = c*(a*b) by the associativity of *.
Q.E.D.
Attachments

172.3 KB Views: 369