Question

Brett has been studying a type of bacteria that doubles every month. Originally, there were 5 bacterial cells. He wants to know how many there will be after 42 months. Which equation should he use?

A a42 = 5(2)42 - 1
B a42 = 5(2)(42)
C a42 = 5(2)42
D a42 = 5(2)(42 - 1)

Answer 1

a42 = 5(2)^42 − 1

Step-by-step explanation:

A is the right answer

Answer 2

Originally, there were only five bacterial cells. After one month, the amount of bacteria is doubled with ten bacteria. The growth is represented by the formula:
a42 = 5 x 2^1
After 42 months, the growth can be solved using this formula:
a42 = 5 x 2^42