A SERIES OF MATHEMATICAL TEXTS EDITED BY EARLE RAYMOND HEDRICK THE CALCULUS By ELLERY WILLIAMS DAVIS and WILLIAM CHARLES ANALYTIC GEOMETRY AND ALGEBRA By ALEXANDER ZIWET and LOUIS ALLEN HOPKINS. By ALEXANDER ZIWET and LOUIS ALLEN HOPKINS. By ALFRED MONROE KENYON and LOUIS INGOLD. By ALFRED MONROE KENYON and LOUIS INGOLD. WITH WITH By JOHN WESLEY YOUNG and FRANK MILLETT MORGAN. By ERNEST BROWN SKINNER. ELEMENTS OF PLANE TRIGONOMETRY WITH COM- By ALFRED MONROE KENYON and LOUIS INGOLD. ELEMENTS OF PLANE TRIGONOMETRY WITH BRIEF By ALFRED MONROE KENYON and LOUIS INGOLD. THE MACMILLAN TABLES Prepared under the direction of EARLE RAYMOND HEDRICK. By WALTER BURTON FORD and CHARLES AMMERMAN. By WALTER BURTON FORD and CHARLES AMMERMAN. SOLID GEOMETRY By WALTER BURTON FORD and CHARLES AMMERMAN. CONSTRUCTIVE GEOMETRY Prepared under the direction of EARLE RAYMOND HEDRICK. JUNIOR HIGH SCHOOL MATHEMATICS By W. L. VOSBURGH and F. W. GENTLEMAN. This book is issued in a form identical with that of the books announced above. BY WALTER BURTON FORD PROFESSOR OF MATHEMATICS, THE UNIVERSITY OF MICHIGAN AND CHARLES AMMERMAN THE WILLIAM MCKINLEY HIGH SCHOOL, ST. LOUIS New York THE MACMILLAN COMPANY 1919 All rights reserved COPYRIGHT, 1919, BY THE MACMILLAN COMPANY. Set up and electrotyped. Published April, 1919. 632306 C Norwood Press J. S. Cushing Co. - Berwick & Smith Co. Norwood, Mass., U.S.A. PREFACE THE present book forms Volume I of a two-volume series on high school algebra and embodies an especial effort to connect the elements of algebra in a clear and forcible manner with the affairs of every-day life. To this end a large variety of applied problems have been introduced and an unusual number of illustrative diagrams used in connection with both the reading matter and the exercises. At the same time, the text follows a distinctly logical line of development, thus affording that drill in accurate thought and expression which should characterize all the mathematical work of the high school. In brief, the presentation is intended to bring algebra into most intimate connection with nature while preserving its fundamental disciplinary values. This, we believe, is the demand, and properly so, of teachers and educators to-day. Among the special features may be noted the abundance of exercises and the care with which they have been selected and graded. Problems of more than average difficulty have usually been accompanied with a hint in order that the pupil's time and energy may be reasonably conserved. At the end of the volume will be found an extensive list of supplementary exercises suitable for class use, in addition to those given in the body of the text. It may be noted also that, as in the authors' Plane and Solid Geometry, the book is so arranged that certain topics may be omitted, at the discretion of the teacher, without interfering with the |