Math: Simple but Hidden Calculus

[zakuArbor]

5 = 5 * 1 or 5 = 5/1 is obvious but in math there's lots of techniques that make sense but are not as obvious to the students

• technique for delta-epsilon proofs: |x + y + (x - y)| (think about the open ball proof)
• integration by parts where you take 1 as u
• the derivative of $e^x$ is $e^x$ but it's actually $e^x \cdot (x)'$

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why is $e^{i\pi}$?

• https://www.youtube.com/watch?v=v0YEaeIClKY
• https://www.youtube.com/watch?v=-dhHrg-KbJ0
• https://www.youtube.com/watch?v=AAir4vcxRPU