Return to Question

Let's see., examples. I put Positive primes represented by indefinite binary quadratic form with this in mind. Cohen says that $\mathbb Q(\sqrt {205})$ has class number 2. There are four classes of indefinite binary forms of discriminant 205, and $u^2 - 205 y^2 = -4$ is impossible. So, we went from 4 to 2...

Let's see., examples. I put Positive primes represented by indefinite binary quadratic form with this in mind. Cohen says that $\mathbb Q(\sqrt {205})$ has class number 2. There are four classes of indefinite binary forms of discriminant 205, and $u^2 - 205 y^2 = -4$ is impossible. So, we went from 4 to 2...

Jyrki Lahtonen has suggested I write a blog post relating binary quadratic forms to quadratic field class numbers, http://math.stackexchange.com/questions/209512/binary-quadratic-forms-over-z-and-class-numbers-of-quadratic-%EF%AC%81elds/209543#comment1727526_209543

Jyrki Lahtonen has suggested I write a blog post relating binary quadratic forms to quadratic field class numbers, https://math.stackexchange.com/questions/209512/binary-quadratic-forms-over-z-and-class-numbers-of-quadratic-%EF%AC%81elds/209543#comment1727526_209543