Sequences and Series

Arithmetic Sequences
An arithmetic sequence is a sequence where the common difference (d) between consecutive terms is constant.
d=T_{2}-T_{1}=T_{3}-T_{2}=T_{n}-T_{n-1}
The general term of an arithmetic sequence is
T_{n} = a+(n-1)d
where a is the first term and d is the common difference.

Geometric Sequences
A geometric sequence is a sequence where the common ratio (r) between consecutive terms is constant.
r= \frac{T_{2}}{T_{1}}=\frac{T_{3}}{T_{2}}=\frac{T_{n}}{T_{n-1}}
The general term of a geometric sequence is
T_{n} = ar^{n-1}
where a is the first term and r is the common ratio.