Let k:= {s+t(sqrt)2 : s, t exist in Q (rational numbers). Show that K satisfies the following:

1. If x,y exist in K then x+y exists in K and xy exists in K

2. If x is not 0 and x is in K then 1/x is in K

(Thus the set K is a subfield of R. With the order inherited from R the set K is an ordered field that lies between Q and R)

Also im not sure what this little tidbit means either

Thank you!