Quadratic equations

[user44]

which of the following are quadratic equations?

y = 1/x
xy=1
x=y^2
y=x^2 + z^2

[Leaderboard]

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Welcome to the forums! Since GregMat (who is a very chill person) doesn’t have any specific formatting rules when it comes to asking questions on the forums, I feel like there should at least be a reference text of some sort that can help people ask better questions and make the process more enjoyable for those who try to answer them. The Golden Rule: Imagine You’re Trying To Answer the Question Before you post your question about GRE preparation, practice questions, or strategies, try to put y…

[user44]

Hi Leaderboard, sorry I couldn’t attach the question screenshot because this was a question that was borne out of my own rumination.

I understand that quadratic equations means highest degree is 2. By this logic, y=1/x is out. But the other 3 examples i gave, their degrees are 2, so are they all quadratic equations? Wanted to confirm.