Answer:
The explicit form for this sequence is
for all
.
Explanation:
The explicit form of an arithmetic sequence of numbers is given by the formula
, where
is the first term of the sequence,
is the difference between two consecutive terms of the sequence, and
.
We know that the first four elements for the arithmetic sequence are
.
To find the general formula for this problem we only need to calculate
in the above formula.
For n=2, we have

if we replace
and
and solve for
we obtain


Therefore the explicit form is
for all
.