CHAPTER 1: LINEAR RELATIONS AND FUNCTIONS SECTION 1-1 Relations and Functions Objectives Determine whether a given relation is a function Identify the domain and range of a relation or function Evaluate functions What is a relation? A pairing of elements of one set with elements of a second set is called a relation. The first element of an ordered pair is the abscissa. The second element of an ordered pair is the ordinate. The set of abscissas is called the domain and the set of ordinates is called the range of a relation. Example 1 State the relation of the windchill data as a set of ordered pairs. Also state the domain and range of the relation. Answer: (5,19), (10,3), (15,-5), (20,-10), (25,-15), (30,-18) D = 5, 10, 15, 20, 25, 30 R = 19, 3, -5, -10,-15,-18 Wind Speed (mph) 5 10 15 20 25 30 Windchill Temperature (F) 19 3 -5 -10 -15 -18 Example 2 The domain of a relation is all consecutive integers between -2 and 2. The range y of the relation is 2 less than twice x, where x is a member of the domain. Write the relation as a table of values and as an equation. Then graph the relation. x -1 0 1 Equation: y = 2x – 2 y -4 -2 0 Example 3 State the domain and range of the relation D = all real numbers R = all negative numbers and zero A function is a relation in which each element of the domain is paired with exactly one element of the range. Function: One to One ( Every x has a different y) Example: y = 3x -5 Function: One to Many (Several x ’s have the same y) Example: y = x 2 NOT A FUNCTION IS MANY TO ONE!! EXAMPLE: x = y 2 Vertical Line Test If a vertical line drawn on the graph of a relation passes through no more than one point of the graph, then the relation is a function. This is called the vertical line test. Function Notation Any letter may be used to denote a function. In function notation, the symbol f(x) is read f of x and is the value of the function f at x. X is called the independent variable and y is called the dependent variable because the value of y depends upon what x you put in to the function. Homework HW#1 Section 1-1 Pp.10-12 #17, 18, 20, 21, 24, 25, 26, 29, 31, 33, 38, 39, 41, 45, 55, 57