Page 21 - Math SL HB Sem 1

UENCE ANDS ERIES

GEOMETRIC SEQUENCE

Definition: A sequence

U1 U
, 2,Uy, -.., U o, - -. ,
is called a geometric
sequence ( or progression
), ifthere exists
a nonzero constant r, called a common ratio, such that

forn> I
ll,
t

In general if a Gp has a first term a,, and a common ratio r, the geometric
sequence is
u, , urr, u.,r2 ..., urf n-t
,
JJJ
First term third
nth term

term
The n" term is un: urrn-,

Examplc I
tcrm for
Irind the nrh tenn and the 8
-3,9,-27,81
,.

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