class 9/10
Mathematics for Class 9 and 10 1.1 Revision The concept of a set is fundamental in all branches of mathematics. Recall that a set is a well defined collection of distinct objects which are called its elements. The sets are usually denoted by A, B, C , . . . X, Y, Z and the elements by a, b, c, . . x, y, z. If a is an element of a set A, we write a ∈ A and read "a belongs to set A" and if a is not an element of a set A, we write a ∉ A and read "a does not belong to set A". 1.2 Some Important Sets of Numbers Following notations will be used for sets of numbers: Set of Natural Numbers : N = {1, 2, 3, . . .} Set of Whole Numbers : W = {0, 1, 2, 3, . . .} Set of Integers : Z = {0, ±1, ±2, ±3, . . } Set of Positive Prime Numbers : P = {2, 3, 5, 7, 11, . . . } Set of Odd Numbers : O = {±1, ±3, ±5, . . . .} Set of Even Numbers : E...