a Check if there is a common ratio. If there is, find it.
B
b Use the function you write in Part A.
A
a f(n)=6(6)^(n-1)
B
b 4 days
Practice makes perfect
a We will begin by making a table that shows the number of people who have received the email at the end of the first three days.
We see that there is a common ratio of 6, meaning it is a geometric sequence. The nth term of a geometric sequence can be found by the function f.
f(n)= a_1 r^(n-1)
In this function a_1 is the first term and r is the common ratio. We can now write the function that represents the number of people who have received the email after day n since we know a_1= 6 and r= 6.
f(n)= 6( 6)^(n-1)
b To find after how many days 1296 people have received the email, we need to find the value of n for which f(n)=1296.
