Exponential Growth and Decay

Which of the following represents exponential growth?

• $f\left(x\right)=-\left(\frac{5}{4}\right)^x$

• $f\left(x\right)=4e^{-x}$

• $f\left(x\right)=-e^{-x}$

• $f\left(x\right)=2\left(.68\right)^x$

Rewrite $y\ =\ a\left(.38\right)^{\frac{t}{12}}$  in either  $y=a\left(1+r\right)^t\ \ or\ \ y=a\left(1-r\right)^t\ \ \ form.$  Tell what the % growth or decay is.

• 7.75% decrease

• 7.75% increase

• 92.25% increase

• 92.25% decrease

 $Rewrite\ y\ =\ a\left(1.37\right)^{\frac{t}{15}}\ \ in\ either\ y=a\left(1+r\right)^t\ or\ \ y=a\left(1-r\right)^t\ \ and\ give\ the\ \%\ increase\ or\ decrease.$  

• 102.12% growth

• 102.12% decay

• 2.12% growth

• 2.12% decay

If you deposit $20,000 in an account paying 3.25% compounded quarterly, how much will it be worth after 15 years?

• $32,564.81

• $32,543.35

• $32,773.36

• $32,500.72

If you deposit $10,000 in an account paying 3.75% compounded continuously, how much will it be worth after 12 years?

• $15,683.12

• $15,672.12

• $15,651.94

• $15,691.08

 $Simplify\ \ \left(-2e^{4x}\right)^5$  

•  $10e^{20x}$  

•  $-10e^{20x}$  

•  $32e^{20x}$  

•  $-32e^{20x}$