This textbook is the final part of a two-year mathematics course for secondary schools. The new edition of the textbook has been supplemented and revised. Its mathematical content allows you to achieve the planned educational results provided for by the Federal State Educational Standard of Basic General Education. In the revised version, special categories by type of activity are highlighted in the exercise system. Also specially allocated tasks for oral work, building tasks, ancient tasks and tasks of increased difficulty. Each chapter of the textbook is supplemented with historical information and interesting and entertaining tasks.