Is it possible that at 7:50 there's a mistake with the simplification steps that you skipped? Multiplying through delta_x^2 wouldn't make it dissapear but rather would be multiplied by the numerator of d^2/dy^2 and likewise for delta_y^2 with d^2/dx^2, since it's a sum, right? Thanks for your response!
Nice explanation
Is it possible that at 7:50 there's a mistake with the simplification steps that you skipped? Multiplying through delta_x^2 wouldn't make it dissapear but rather would be multiplied by the numerator of d^2/dy^2 and likewise for delta_y^2 with d^2/dx^2, since it's a sum, right?
Thanks for your response!
Look at the chapter in my lecture notes.
delta_x = delta_y