Soviet Era Math Book for Beginners and Mathematical Experts

This book states that it is written with beginners in mind but it can also be of use to expert mathematicians. The first half of the book is on Differential Equations and the second half is on the Calculus of Variations. In this video I will show you this book and I will also solve a differential equation from the book near the end of the video. I purposely picked one that was really simple so if you know some calculus you should be able to follow along or solve it yourself. Originally this book was written in Russian but it was translated to English and published by Mir Publishers. Mir Publishers was/is a publishing company that translates Russian books to various languages. I first heard of Mir from the comments here on the channel so thank you to everyone for the book suggestions! The book is called Differential Equations and the Calculus of Variations and it was written by Lev Elsgolts. Here is the book: (this is my affiliate link) 0:00 The Book 7:43 The Pro