what a nice functional equation!

what a great "double" functional equation!

an absolutely surprising final solution to this functional equation.

the craziest of differential equations!

a nice functional equation

History of Calculus 12: Cauchy

How Imaginary Numbers Were Invented

can you guess the tricks?

a notorious functional equation.

Section 4.1 Power Rule and Examples

I Solved An Interesting Nonstandard Equation

Taylor series | Chapter 11, Essence of calculus

a surprisingly complicated sum from a viewer

Functional Equation

The Oldest Unsolved Problem in Math

How to Take the Factorial of Any Number

Algebra - How To Solve Equations Quickly!

a particularly pretty product

a twist on a classic circle problem

Your new favorite pi approximation.

the coolest trick for sums