“In mathematics, a quadratic form is a polynomial with terms all of degree two. For example, 
“Quadratic forms are not to be confused with a quadratic equation which has only one variable and includes terms of degree two or less”(ibid)
Also, this video from Khan Academy was helpful: Expressing a quadratic form with a matrix
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Disclaimer:
I am not a professional in this field, nor do I claim to know all of the jargon that is typically used in this field. I am not summarizing my sources; I simply read from a variety of websites until I feel like I understand enough about a topic to move on to what I actually wanted to learn. If I am inaccurate in what I say or you know a better, simpler way to explain a concept, I would be happy to hear from you :).
