A rare bacterial culture is being grown in a lab. As the days progress, the cells multiply and grow.

After 1 day, there is only 1 cell.
After 2 days, there are 8 cells.
After 3 days, there are 18 cells.
After 4 days, there 31 cells.

Which recursive equation represents the pattern?

A. an=an-1+3n+1

Question

A rare bacterial culture is being grown in a lab. As the days progress, the cells multiply and grow. 

After 1 day, there is only 1 cell. 
After 2 days, there are 8 cells. 
After 3 days, there are 18 cells. 
After 4 days, there 31 cells. 

Which recursive equation represents the pattern? 

A. an=an-1+3n+1 <- my answer
B. an=an-1+3(n+1) 
C. an=an-1+(n+3) 
D. an=an-1+(n-3)

lfghjyt · Answer

Substituting the values for day 4, 

18 + 3*4 + 1 = 31 
18 + 3(4 + 1)= 33 
18 + (4 + 3) = 25 
18 + (4 - 3) = 19 

Thus the equation is, 

a˅n = a˅(n–1) + 3*n + 1 .... ˅ means sub

liv1234 · Answer

@lfghjyt Does that mean I'm right?

liv1234 · Answer

@sissyedgar

liv1234 · Answer

@inkyvoyd

sissyedgar · Answer

I think it does but i'm not sure.
It looks like it to me tho.