Question

What is the next four terms in the arithmetic sequence: 12, 16, 20,...?

Answer 1

`a_4=24`

Explanation:

We know that in an arithmetic progression we have `a_1=12, a_2=16, a_3=20` and we're looking for `a_4`. In a arithetic sequence the common difference is given by $$d=a_i-a_{i-1}$$ for 'any working `i`.'

So: $$d=a_3-a_2=20-16=4$$ or as well $$d=a_2-a_1=16-12=4$$

Now simply $$a_4=a_3+d=20+4=24$$