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### Transcript of Indices - · PDF fileAdding and Subtracting with Indices Two expressions in index form are ......

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Indices

Indices

ACMNA: 209, 210, 212, 264

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Indices

SERIES TOPIC

J 4

Indices is the plural for index. An index is used to write products of numbers or pronumerals easily. For example 42 is actually a shorter way of writing 4 4# . The 2 is the index. Another word for index is exponent.

INDICES

What do I know now that I didn't know before?

Answer these questions, before working through the chapter.

I used to think:

Answer these questions, after working through the chapter.

But now I think:

What is scientific notation?

How are indices used to write very large and very small numbers?

What are indices? (What are exponents?)

What is scientific notation?

How are indices used to write very large and very small numbers?

What are indices? (What are exponents?)

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Indices

SERIES TOPIC

J 4

Basics

Index Notation

Index notation is used to write a product of a number with itself in an easier way. For example:

5 5 5 5 5 6254# # # = =

Index or exponent or power

Basic numeral

Base

So when multiplying a number, say 6, by itself 100 times, its easier to write 6100 instead of 6 6 6 ...# # # (100 times).

If the index is 1 we usually make it invisible so we write 7 instead of 71.

Simplifying like terms

Can be simplified (like terms) Cannot be simplified (unlike terms)

Same index

5 5 2 53 3 3+ = ^ h

Same base

Different indices

4 48 6-

Different base

2 43 3+

Two expressions in index form are like terms if they have the same base AND they have the same index.

6 4 4 6 43 3 2 3 3+ + + +

Like terms

Like terms

46 6 4 43 3 3 3 2= + + + +^ ^h h

2 2 46 43 3 2= + +^ ^h h

Like terms grouped together

Simplify like terms

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Indices

SERIES TOPIC

J 4

Basics

Same base

Same base

Subtract indices

Multiplication with Indices

Consider the product 4 4 4 44 4 4 4 42 3 5 2 3# # ## #= = = +^ ^h h . In the product, the base is the same and the indices have been added together. In general you can apply the formula for multiplication with indices:

a a am n m n# = +

a a am n m n' = -

Multiplying terms with indices

a

a

b

b

4 9 4 9 36 36t t t t t t2 5 2 5 2 5 7# # # #= = =+

Coefficients multiplied separately

Coefficients multiplied separately

Coefficients divided separately

Coefficients divided separately

Same bases grouped together

Same bases grouped together

REMEMBER A coefficient is the number before the variable in an expression. Eg. The coefficient of 2x is 2.

5 3 5 3 15 15p q p q p p q q p q p q3 4 2 3 2 4 3 2 4 1 5 5# # # # # #= = =+ +

Division with Indices

If we divide 7 7 7 7 7 1 7 7 .7 7 7

7 7 7 7 77 7 77 7 75 3 2 2 5 3'

# ## # # #

# ## ## # #= = = = = -c cm m

In the division, the second index (3) has been subtracted from the first (5). In general, apply this formula for division with indices:

Dividing terms with indices

y y y y

y

y

20 4 20 4

5

5

7 2 7 2

7 2

5

' ' '=

=

=

-

^ ^h h

21 7a b c a bc a a b b c c21 75 4 6 4 4 5 4 4 6 4' ' ' ' '= ^ ^ ^ ^h h h h

a b c

ab c

3

3

5 4 4 1 6 4

3 2

=

=

- - -

• 4 100% IndicesMathletics 100% 3P Learning

Indices

SERIES TOPIC

J 4

BasicsQuestions

1. Write in expanded form:

a

a

d

d

g

g

b

b

e

e

h

h

c

c

f

f

i

52 = 64= 9

3=

2 3- =^ h31 5 =` j

21 4- =` j

x2 = x y3 3 = a b c3 2

=

2. Identify the base, index and basic numeral of each of the following:

10

Base =

Index =

Basic numeral =

32

Base =

Index =

Basic numeral =

21 3` j

Base =

Index =

Basic numeral =

1 5-^ h

Base =

Index =

Basic numeral =

26

Base =

Index =

Basic numeral =

3 2-^ h

Base =

Index =

Basic numeral =

1 4^ h

Base =

Index =

Basic numeral =

43

Base =

Index =

Basic numeral =

3. Identify the following values:

a What is the basic numeral of 4 to the index 3?

b What is the base of an expression with index 2 and basic numeral 16?

c What would the index of an expression be if the basic numeral is 81 and the base is 3?

d What is the index in an expression with base 7 and basic numeral 343?

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Indices

SERIES TOPIC

J 4

Questions Basics

4. Use like terms to simplify the following in index form (if possible):

a

a b

c d

e f

g h

i

b

c d

e f

2 23 3+ =

4 5 53 3- =^ h

3 4 6 2 3 62 3 2 3+ + + =^ ^h h

4 2 42 2+ =^ h

7 7 72 2+ + =

3 2 3 4 3 5 3 12 3 2 3- + - + + =^ ^ ^h h h

5. Find the following products in simplest index form:

3 33 6# =

2 23 7#- - =^ ^h h

21

21

213 5# # =` ` `j j j

x y y x2 4 3# # # =

6 3w v w v4 3 2 8# # # =

5 5 54 3# # =

2 22 5#- - =^ ^h h

qq3 7# =

c a cab 410 2 4 3# =

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Indices

SERIES TOPIC

J 4

BasicsQuestions

6. Find the following products in simplest index form:

a b

c d

e f

g h

i

8 812 5' =

5 511 6'- - =^ ^h h

4

412

19

=

36 9a b a b8 9 5 6' =

24 8e f e f13 6 5 5' =

7 721 15' =

53

539 2' =c cm m

r s r s5 4 3 2' =

x y

x y

6

547 3

11 4

=

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Indices

SERIES TOPIC

J 4

Knowing More

Raising Indices to Indices

We use what we know about multiplying terms with indices, to find a rule for raising indices to indices. Consider for example:

2 2 2 2 242 4 4 8 4 2#= = = #^ h

Notice that the base remains the same and we find the product of the indices. In general, apply the formula

Same base Multiply Indices

a amn mn

=^ h

Raising indices to indices

a

b

3 3 352 5 2 10= =#^ h

4 4 4x x x3 3 3= =#^ h

More Index Laws

andab a bba

bam m m mm

m= =^ ch m

If a product or fraction is raised to an index, then the index applies to each term.

Brackets with indices

a b

c d

x x

x

3 3

27

3 3 3

3

=

=

^ h 4

256

256

pq p q

p q

p q

4 24 4 4 2 4

4 2 4

4 8

=

=

=

#

^ ^h h

x x

x

2 2

8

3

3

3

3

=

=

` j a b a b

a b

53

5

3

259

3 2

2

2 3 2 2

6 2

=

=

c ^m h

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Indices

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Knowing More

The Zero Index

1a aaam mm

m0= = =-

when1 0a a0 !=This means

Anything raised to an index of 0 is 1.

The zero index

4 1 5 1 100000 1 1 1 1 1 1a b x a b5320 0 0 0 0 0 0 3 2 0= = = = = = - = = = = + = = = = =^ ` ^ ^h j h ha

b

c

a

b

6 2 6 1 2 310 0+ = + =^ ^h h

7 1 7 7ab 0 # #= =^ h

Fractional Indices

Lets try figure out what to do when the indices are fractions, such as or p1641

71

.

For example, consider 521

:

1

2

3

Using the index law for multiplication we can say 5 5 521 2 1

= =^ h

Find the square root of both sides to obtain 5 521 2

=^ h

Simplify by cancelling the index of 2 with the square root 5 521=

For any a, we can say a 21

is the square root of the number a. In the same way a 31

is the cube root of a.

Basically, for any n, a n1

is the nth root of a. Always use the formula

a an n1=

Fractional indices

36 36 621= =

8 2x x x8 12 31

31 12

31 4#= =#^ h

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Indices

SERIES TOPIC

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Knowing More

Negative Indices

Lets see if we can use what we know to figure out how to use negative indices such as or3 , x21 10 5- ^ h .

For example:

Negative indices

5 5

55

5

5

5

5

1

55

1

2 0 2

0 2

2

0

2

0

2

2

2`

=

=

=

=

- -

-

-

Since 0 - 2 = -2

Using the division of indices law

According to the zero index law

In general, for negative indices we use the formula:

aa1nn=

-

xx

4 422=

-

53

35

3

59252 2

2

2

= = =-

` `j j

aa

21

21 1= -

221

412

2- = -=-^

^h

h

22

1412

2- =- =--

^ h

1t t

t3 333

1 3

3= =-

c m44

16413

3= =-a b

c d

e

f

g

Negative indices examples

In this example