Patterns and sequences
Weoften need to spot a pattern in order to
predict what will happen next.
In maths, the correct name for a pattern of
numbers is called a SEQUENCE.
The first number in a SEQUENCE is sometimes
called the FIRST TERM; the second is the
SECOND TERM and so on.
6.
Patterns and sequences
Forany pattern it is important to try to spot
what is happening before you can predict the
next number.
The first 2 or 3 numbers is rarely enough to
show the full pattern - 4 or 5 numbers are
best.
7.
Patterns and sequences
Forany pattern it is important to try to spot
what is happening before you can predict the
next number.
1, 2, …… What’s the next number?
8.
Patterns and sequences
Forany pattern it is important to try to spot
what is happening before you can predict the
next number.
1, 2, 4,… Who thought that the next
number was 3?
What comes next?
9.
Patterns and sequences
Forany pattern it is important to try to spot
what is happening before you can predict the
next number.
1, 2, 4, 8, 16, …
What comes next?
10.
Patterns and sequences
Lookat what is happening from 1 TERM to
the next. See if that is what is happening
for every TERM.
5, 8, 12, 17, 23, …, …
+ 3
11.
Patterns and sequences
Lookat what is happening from 1 TERM to
the next. See if that is what is happening
for every TERM.
5, 8, 12, 17, 23, …, …
+ 3 + 4
12.
Patterns and sequences
Lookat what is happening from 1 TERM to
the next. See if that is what is happening
for every TERM.
5, 8, 12, 17, 23, …, …
+ 3 + 4
13.
Patterns and sequences
Lookat what is happening from 1 TERM to
the next. See if that is what is happening
for every TERM.
5, 8, 12, 17, 23, …, …
+ 3 + 4 + 5
14.
Patterns and sequences
Lookat what is happening from 1 TERM to
the next. See if that is what is happening
for every TERM.
5, 8, 12, 17, 23, …, …
+ 3 + 4 + 5 + 6
15.
Patterns and sequences
Lookat what is happening from 1 TERM to
the next. See if that is what is happening
for every TERM.
5, 8, 12, 17, 23, 30, …
+ 3 + 4 + 5 + 6 + 7
16.
Patterns and sequences
Nowtry these patterns:
3, 7, 11, 15, 19, …, …
128, 64, 32, 16, 8, …, …
1000, 100, 10, 1, …, …
5, 15, 45, 135, …, …
Infinite
sequence
So what is a finite
sequence?
CONSIDERTHE FOLLOWING SEQUENCE
•1, 4, 9, 16, 25, …
• What is the value of a (T1 ) ?
• T5 ?
• What is the pattern?
• T1 = 1 = 12
• T2 = 4 = 22
• T3 = 9 = 32
• …
T12 = ?
• Tn = ?
Tn is
called
the
general
term
Sequence is
Describe the pattern,write the next term, and
write a rule for the nth term of the sequence
(a) – 1, – 8, – 27, – 64, . . .
SOLUTION
You can write the terms as (– 1)3
, (– 2)3
, (– 3)3
,
(– 4)3
, . . . . The next term is a5 = (– 5)3
= – 125.
A rule for the nth term is an = (– n)3
.
a.
22.
Describe the pattern,write the next term, and
write a rule for the nth term of the sequence
(b) 0, 2, 6, 12, . . . .
SOLUTION
You can write the terms as 0(1), 1(2), 2(3),
3(4), . . . .
The next term is f (5) = 4(5) = 20. A rule for the
nth term is f (n) = (n – 1)n.
b.
23.
CONSIDERTHIS:
• What isthe pattern? How many dots for the next term?
• What about the 50th
term?
• Need to find general term or the rule first.
…
SERIES
• A seriesis the sum of the terms in the
sequence and is represented by Sn.
• E.g.
• Sn = T1 + T2 + T3 +…+ Tn
• For finite series,
• 1 + 3 + 5 + 7.
• For infinite series,
• 1 + 2 + 3 + 4 +…
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