ok so:
3.(a,b)*(e1,e2)=(a,b)
(ae1,be1+e2)=(a,b)
ae1=a e1=a/a=1
be1+e2=b e2=b-b(1)=0
(a,b)*(1,0)=(a(1),b(1)+0)=a,b
(1,0)*(a,b)=(1(a),0(a)+b)=a,b so it has an identity
4. (a,b)*(a',b')=(1,0)
(aa',ba'+b')=1,0
aa'=1 a'=1/a
ba'+b'=0 b'=-ba'=-b/a
(a,b)*(1/a,-b/a)=(a/a,b/a+(-b/a))=1,0...