These scary large math symbols aren't scary at all and easily explained. The scary parts of maths lie elsewhere. They are discrete, nonlinear or high dimensional and sometimes even the numbers are complex... Or worse.
Knowing that no matter how many times you read the theorem, there's no fucking you'll memorize it for the exam. Oh, and also there are at least 20 of them, and you don't know which one they are going to ask.
I recommend this video and the channel in general. The guy can explain even the most complicated and abstract mathematical concepts in a perfectly clear and understandable way.
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I had to watch the video on quaternions three times to grasp the concept.