The table shows the predicted growth of a particular bacterium after various numbers of hours. Write an explicit formula for the sequence of the number of bacterium.

Hours (n) 1 2 3 4 5
Number of Bacterium 21 42 63 84 105

Question

The table shows the predicted growth of a particular bacterium after various numbers of hours. Write an explicit formula for the sequence of the number of bacterium.

Hours (n)                     1   2   3   4     5
Number of Bacterium 21 42 63 84 105

anonymous · Answer

So as I see it, I must write an explicit formula for the sequence 21, 42, 63, 84, 105.

anonymous · Answer

And based on what my calculator tells me, the answer should be
$$a_{n}=21n$$
Is this correct?

anonymous · Answer

@douglaswinslowcooper Hey, this correct or not? Thanks in advance btw.

anonymous · Answer

Yes, you have nailed it. Who knew a calculator would do that?

anonymous · Answer

May return later tonight. Regards.

anonymous · Answer

Wolfram Alpha x3 and thanks again.

anonymous · Answer

one more if you have the time

anonymous · Answer

I don't have any idea in the slightest how to do the next.