Lesson 4-3 Rate of Change and Slope Obj: The student will be able to 1) Find rates of change and slopes 2) Relate a constant rate of change to the slope of a line HWK: p 248 2-11 all Vocab: 1) rate of change 2) rise 3) run 4) slope

Rate of change: 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑑𝑒𝑝𝑒𝑛𝑑𝑒𝑛𝑡 𝑣𝑎𝑟𝑖𝑎𝑏𝑙𝑒 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑖𝑛𝑑𝑒𝑝𝑒𝑛𝑑𝑒𝑛𝑡 𝑣𝑎𝑟𝑖𝑎𝑏𝑙𝑒

Ex 1) The table shows the cost of mailing a 1-ounce letter in different years. Find the rate of change in cost for each time interval. During which time interval did the cost increase at the greatest rate? Year 1988 1990 1991 2004 2008 Cost (cents) 25 29 37 42

Ex 2) Graph the data from Ex 1 and show the rates of change.

Slope of a line 𝑟𝑖𝑠𝑒 𝑟𝑢𝑛 = 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑦 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑥 Positive slope Negative slope Zero slope Undefined slope

Find the slope of each line Ex 3) Ex 4) (-1, 2) (3, 2)

Ex 5) (0, -3) (5, -5) Ex 6) (-2, 4) (-2, 1)

The greater the absolute value of the slope, the greater the steepness of the line.