prove that S={2a+bi:a,b ε Z} is not closed multiplication where i= √–1???

and with that

Find the continued fraction expansion of √8 and hence or otherwise show that √8

is irrational???

2. Originally Posted by geo2

prove that S={2a+bi:a,b ε Z} is not closed multiplication where i= √–1???

and with that

Find the continued fraction expansion of √8 and hence or otherwise show that √8

is irrational???
$
(2+i)(2-i)=4+1=5 \notin S
$

CB