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Sequence 2.1
Expression
An expression is a mathematical phrase using
numbers or variables or both. 1 + 1 and 3x + 5
are examples of expressions.
sequence
A sequence is an ordered list of numbers, and
each number is called a term of the sequence.
{0, 1, 2, 3, . . .} is a sequence.
Ex1. 5,10,15,20,…
1. Since 10-5=5, 15-10=5, 20-15=5,
then the constant difference is 5.
2. The expression might be 5n.
3.
n
1
2
3
4
3. Check by substituting
postion
position 1 in place of n to see
or
if it works. If it works, then
figure
your expression is “constant
term
5
10
15
20
difference” n. If it does not
5(1)=5
work, then either add or
5(2)=10
subtract by a number to
5(3)=15
make it work out to each
5(4)=20 therefore, the expression is 5n
term. Check the rest of the
Ex2. 8, 13, 18, 23,…
position numbers.
1. Since 13-8=5, 18-13=5, 23-18=5, then the
To Write an expression:
1. Find the constant difference by
subtracting the 2nd term from the 1st
term, 3rd from 2nd , etc.
2. The expression is the constant
difference multiply to position of
each term.
constant difference is 5.
2. The expression might be 5n.
3.
n
1
2
3
4
position
or
figure
term
8
13
18
23
5(1)=5 not 8. Since it does not work,
then 5(1) +3 =8; therefore, try 5n+3
5(2)+3=13
5(3)+3=18
5(4)+3=23 therefore, he expression is
5n+3