Is d^2y/dx^2=(dy/dx)^2? Well, not all the time, but sometimes yes! The video from 2017: https://youtu.be/wohyJ2heLso?si=fbdXzibuq9rRX58x ---------------------------------------- Big thanks to my Patrons for the full-marathon support! Ben D, Grant S, Mark M, Phillippe S. Michael Z, Jan...