1. Algebra, according to the usual definition, is that branch of mathematics in which the quantities. considered are represented by the letters of the alphabet, and the operations to be performed upon them are indicated by signs. In this sense it would embrace almost the whole science of mathematics, elementary geometry alone being excepted. It is, consequently, subject in common use to some limitations, which will be more easily understood, when we are farther advanced in the science. 2. The sign is called plus or more, or the positive sign, and placed between two quantities denotes that they are to be added together. Thus 35 is 3 plus or more 5, and denotes the sum of 3 and 5. Likewise a + b is the sum of a and b, or of the quantities which a and b represent. |