Objective Video Example by Mrs. G Give It a Try Lesson 8.2  Use exponential growth models to set up and solve real-life problems.

Video Objective Video Example by Mrs. G Give It a Try YouTube Textbook Tactics

Example by Mrs. G Objective Video Example by Mrs. G Give It a Try Click to continue. y = a b x y = a (1 + r) t a ≠ 0 initial amount b = 1 + r > 1 growth factor 0 < r < 1 growth rate time period (still independent variable) General Exponential Form Alternate Form Exponential Growth Model

Example by Mrs. G Objective Video Example by Mrs. G Give It a Try Click to continue. y = a b x y = a (1 + r) t General Exponential Form Alternate Form Use the general form when you are told that the amount “doubles” or is some many “times bigger” than the starting amount. Use the alternate form when you are told that the amount increases by a certain percent. The percent, as a decimal, is r. Exponential Growth Model

Example by Mrs. G Objective Video Example by Mrs. G Give It a Try Click to continue. The owner of a 1953 Hudson Hornet convertible sold the car at an auction. The owner bought it in 1984 when its value war $11,000. The value of the car increased at a rate of 6.9% per year. Write a function that models the value of the car over time. – Which model should we use? – What is the initial amount? – What is the growth rate? y = a (1 + r) t a = 11,000 r = 6.9% = 0.069

Example by Mrs. G Objective Video Example by Mrs. G Give It a Try Click to continue. y = 11,000 ( ) t If the auction took place in 2004, what was the approximate value of the car at the time of the auction? Round your answer to the nearest dollar. – y = 11,000 ( ) 20 – y = $41,778 (use a calculator)

Give It a Try Objective Video Example by Mrs. G Give It a Try Bring your work and answer to our next class! You deposit $1,000 into an account that will gain 6% interest compounded every year. a)Write an exponential growth model that represents the amount in the account over time. b)How much money will be in the account after 8 years?