EOC Review #4: Exponential Functions

What is the solution to the equation

255 = 4^x – 1?

• x = 4

• x = 5

• x = 64

• x = 63.5

The recursive formula for a geometric sequence is given as an = a_n-1(1/2) , with a₁ = −128. What are the first four terms of the sequence?

• –128, 64, –32, 16

• –128, –64, –32, –16

• 128, –64, 32, –16

• -1/2 , 1, –2, 4

What is the y-intercept of the function?

• (0,2)

• (0, 3)

• (0,1)

• (0, -2)

What is the y-intercept of the function y=0.10(5)^x - 3?

• (0, -3)

• (-3, 0)

• (0, -2.9)

• (-2.9, 0)

If y = 1.62(0.67)^x, what is the percent rate of change of y for each unit of x?

• 33% increase

• 33% decrease

• 67% increase

• 67% decrease

Write an equation that models the following situation:
Samantha's hair was known to grow very rapidly. It began at a length of 6 in and grew at a rate of 14% a week.

• y=6(0.14)^x

• y=6(1+14)^x

• y=6(1.14)^x

• y=6(0.86)^x

A population of fish starts at 8,000 and decreases by 6% per year. What is the population of fish after 10 years?

• 14327

• 4309

• 839

• 7680

The value of a car is $15,000 and depreciates at a rate of 8% per year. What is the decay factor?

• ^.08

• ^1.08

• .92

• 8

A type of bacteria doubles every 8 hours. If you started with 8 bacteria in a Petri dish, how many bacteria would you have after 24 hours?

• 1.68 x 10⁷ bacteria

• 64 bacteria

• 1.34 x 10⁸ bacteria

• 56 bacteria

A form of the element thullium, Tm-167, has a half-life of 9 days. At the end of an experiment that lasted 63 days, there were 9 grams of Tm-167 left. How much Tm-167 was there at the beginning of the experiment?

• 8.3 x 10¹⁹ grams

• 1,152 grams

• 0.07 grams

• 576 grams