Binary quadratic form: Difference between revisions

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"Composition" can also refer to a binary operation on representations of integers by forms. This operation is substantially more complicated{{citation needed|date=March 2017}}<!--<ref>{{harvnb|Shanks|1989}}</ref> full citation not in article yet --> than composition of forms, but arose first historically. We will consider such operations in a separate section below.

Composition means taking 2 quadratic forms of the same discriminant and combining them to create a quadratic form of the same discriminant, itas isfollows afrom generalization of the 2-square[[Brahmagupta's identity <math>\left(a^2 + b^2\right)\left(c^2 + d^2\right) = \left(ac-bd\right)^2 + \left(ad+bc\right)^2</math>]].

=== Composing forms and classes ===