Infinite 9 is a textbook for lower secondary school mathematics.In this book, you will explore the properties of right angles and solid shapes as well as lines and other graphs. You will also learn about functions and simultaneous equations. In addition, you will revise the topics of lower secondary school mathematics and continue using GeoGebra and programming with Python. In each chapter, there are clearly stated goals that let you know what the aim of your studies is. To support your learning, you can also use the digital materials that accompany this textbook.