Arithmetic Sequences & Series (Leaving Cert Mathematics): Flashcards

A sequence summed up

An arithmetic sequence summed up

$S_n=\frac{n}{2}[2a+(n-1)d]$

Sum of first $n$ terms: $S_n=T_1+T_2+...+T_n$

First term of sequence

Common difference

Find first few terms, identify by observation

Rearrange $T_n$ and equate with given term

$T_n=dn+(a-d)$

$a=-4$

$d=2$

$500$