Problem :
Define the arithmetic sequence an = 4n - 3 recursively.
a1 = 1.an+1 = an + 4.
Problem :
Define the arithmetic sequence a1 = 6; an+1 = an - 2 explicitly.
an = - 2n + 8
Problem :
What is the sum of the first six terms of the sequence an = 2n + 6?
S6 =
(a1 + a6) = 3(8 + 18) = 78.
Problem :
What is the sum of the first 45 terms in the arithmetic sequence a1 = 3;
an+1 = an + 5?
S45 = 45a1 +
(45d - d )= 135 + (22.5)(220) = 5085.