Homework Statement
let S be the ring of all pairs (q,s) with q,s being rational.
define (q,s) + (q',s') = (q+q',s+s')
and (q,s)(q',s') = (qs'+q's,3qq'+ss')
Prove that S is a field.
Homework Equations
Try proving that it is isomorphic to something else using the First homomorphism...