Middle school mathematics: 8th & 9th grades

Mathematics is not a collection of puzzles or riddles designed to test your intelligence. It is a language for describing and interacting with the world. Deliberately distancing ourselves from dry math textbooks — presentations of different subjects without connections, each time with the same format: definitions, axioms, lemmas, theorems, corollaries, and minimal examples, all laid out densely in a forest of symbols — we present mathematics without tricks, without challenges, without cryptic notations, and without bluff, using the simple and natural language of everyday life. We explain where all the tools come from (arithmetic, algebra, geometry, analytic geometry, functions, calculus, algebraic structures, linear algebra, matrices, probability, statistics, algorithmics), how they are interconnected, and what they are used for in mathematics, physics, engineering, and other fields. We aim to be understood by everyone, especially young people who grasp complex technologies and games when it’s for fun. However, this does not mean that mathematical concepts do not sometimes require effort and reflection. The 8th & 9th grade mathematics book completes the middle school math curriculum and even introduces some high school concepts. Middle school offers a comprehensive foundation of math applicable to everyday life. We encountered much of this material in primary school, though primarily as a set of methods; in secondary school, we delve into the underlying principles and broaden our view of mathematics as a whole. In our subsequent high school volumes, we begin to present the mathematics essential for engineers, physicists, professionals in various other disciplines, as well as future mathematicians. If you study and understand all the mathematics presented in our books from 6th to 12th grade, you will be well-prepared for college courses and beyond. Our philosophy of mathematics and how to teach it: https://tinyurl.com/5eejvhzx Table of contents: https://tinyurl.com/57vw2fvf Preface: https://tinyurl.com/mryy2hnt Free lesson: https://tinyurl.com/4rh9a23w Index: https://tinyurl.com/3pjnw2v7 Erratum: https://tinyurl.com/mrxrhyc2