MYTH

You can’t fold a piece of paper in half more than 7 times

TRY IT

• How many times can you fold a piece of paper in half? Motivational music

What changes could you try to make this possible?

PaperMethodEquipment

WHY is it so difficult?

THE MATH

• If notebook paper is .003 in thick how think is the stack after 5 folds, 6 folds, 7 folds…

• How many pieces of paper are you actually trying to fold?• Create a table to record the amount of paper with each fold.

FOLD # of paper THICKNESS(in)

0 1 .003

1 2 .006

2 4 .012

3 8 .024

4 16 .048

5 32 .096

6 64 .192

7 128 .384

??

Watch the pros?

• Video of mythbusters attempt to fold paper

Unit 2

Exponential FunctionsGraphing

Growth/Decay

Exponential functions

• An exponential function has the form:A few requirements:

An exponential function has the x as the exponent!!

xbay )()1,0( ba

xbaxf )()( Exponent

BaseFunction notation

Y-int

DECAY IF : 0 < b < 1 “ b is a fraction less than one” Growth if: b > 1

x

xf3

1)(

xxg )3(2)(

52)( 4 xxh

kaby hx )(

Word problems

• You can model exponential growth or decay with:

tray )1( Ending amount

Initial amount

Rate(decimal)

Time

Example

• If you invest $1000 in a savings account that pays 5% annual interest. How much money will you have after six years?

• How many years will it take for the account to grow to at least $1500?

Example

• A new car is worth $20,000 and is expected to depreciate 12% each year. How much will the car be worth after 10 years?

• How long will it take for the car to be worth half it’s original value?

Practice

• Pg 439 #18-28, 26, 27, 28, 31, 32