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 9 cells.
After 3 days, there are 20 cells.
After 4 days, there are 34 cells.

Which recursive equation represents the pattern?

4 answers

What are your choices?
an=an-1+3n

an=an-1+(n+2)

an=an-1+3(n+2)

an=an-1+(3n+2)

I thought it was the last one but am not sure and am trying to help my grandson.
well, the amounts added are 8,11,14
They differ by 3, so it will look like

a(n) = a(n-1) + 3n + ?

3n looks like 3,6,9, so we have

a(n) = a(n-1) + 3(n-1)+5 = a(n-1)+(3n+2)

so you are correct
thank you