SCHOOL ALGEBRA BY FLETCHER DURELL, PH.D. HEAD OF THE MATHEMATICAL DEPARTMENT IN THE DURELL'S MATHEMATICAL SERIES ARITHMETIC Two BOOK SERIES Elementary Arithmetic, THREE BOOK SERIES Book One, Book Two, Book Three, ALGEBRA Two BOOK COURSE Book One, Book Two, Book Two with Advanced Work, INTRODUCTORY ALGEBRA, SCHOOL ALGEBRA, GEOMETRY PLANE GEOMETRY, SOLID GEOMETRY, PLANE AND SOLID GEOMETRY, TRIGONOMETRY PLANE TRIGONOMETRY AND TABLES, PLANE AND SPHERICAL TRIGONOMETRY LOGARITHMIC AND TRIGONOMETRIC [15] COPYRIGHT, 1911, 1914, BY CHARLES E. MERRILL CO. HARVARD LIBRARY Truth. Ancpcomes a truth so s it cannatal/pend upon and th PREFACE simbolik truth THE main object in writing this SCHOOL ALGEBRA has been to simplify principles and give them interest, by showing more plainly, if possible, than has been done heretofore, the practical or common-sense reason for each step or process. For instance, at the outset it is shown that new symbols are introduced into algebra not arbitrarily, but because of definite advantages in representing numbers. Each successive process is taken up for the sake of the economy or new power which it gives as compared with previous processes. This treatment should not only make each principle clearer to the pupil, but should give increased unity to the subject as a whole. We believe also that this treatment of algebra is better adapted to the practical American spirit, and gives the study of the subject a larger educational value. Among the special features of this SCHOOL ALGEBRA, the following may be mentioned: A large number of written problems are given in the early part of the book, and these are grouped in types which correspond in a measure to the groups used in treating original exercises in the author's GEOMETRY. Many informational facts are used in the written problems. The central and permanent numerical facts in various departments of knowledge have been collected and tabulated on pages 496-504 for use in making problems. Similarly the most important |