Relations and Functions Chapter 4 Relations and Functions

Function: is a link between two numbers that vary Variables: are quantities with changing values if a value doesn’t change then it is called a constant There are 2 kinds of variables: independent dependent

The two types of variables Dependent “y” variable This variable reacts to the changes in the independent variable Independent “x” variable This variable causes the dependent variable to change.

How to Display Variables Table of Values Graphing X (independent) Y (dependent) Y dependent X (independent) y (dependent) x independent You must always put the variables in the right place Remember to be careful about the “scale”

How to Graph a Function Identify independent and dependent variables Draw a Cartesian Plane on graph paper Determine the scale of the “x” and “y” axis Make a table of values Carefully put all coordinates from table of values onto the Cartesian Plane (graph) Use a ruler to connect the coordinates

Example: I pay my babysitter $5/hr. Dependent variable: Amount she gets paid Independent Variable: The number of hours that she works Table of Values Draw a Cartesian Plane Number of hours she works 1 2 4 Amount she gets paid ($) 5 10 20

Graphing the coordinates. (0,0), (1,5) etc.. Decide on a scale for each axis. Place the coordinates on the graph. Connect the coordinates with a ruler Workbook page 96 act #2 and then page 99 #2 Textbook page 113 # 1 (name the variables precisely..) and #2 20 15 10 5 1 2 3 4 5

Independent Dependent Temp length of the rod Time amount wasted Time height of plant # of days amount of oil intank