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math guide - 34.4

34.1.2.1- Factorial

A compact representation of a series of increasing multiples.

n! = 1 2 3 4 … n

0! = 1

Figure 34.4 The basic factorial operator

34.1.3Exponents and Logarithms

The basic properties of exponents are so important they demand some sort of

mention

 

 

 

 

 

 

 

 

 

 

1

 

 

 

 

( xn) ( xm) = xn + m

x0

 

 

 

 

 

--

 

 

 

 

= 1 , if x is not 0

xn

= n x

 

 

 

 

 

p

 

1

 

m

 

 

 

 

n

 

 

x

=

 

---

 

n

 

m

 

n m

 

 

----

x

n

=

x

( x )

= x

 

 

 

 

x

p

 

 

 

----------

 

 

 

 

 

 

 

 

 

 

 

 

( xm)

 

 

 

( xy) n

= ( xn) ( yn)

 

x

 

n x

 

 

 

 

 

=

( xn) m

= xn m

 

n

-

------

 

 

 

 

 

 

 

y

 

n y

Figure 34.5 Properties of exponents

• Logarithms also have a few basic properties of use,

math guide - 34.5

The basic base 10 logarithm:

 

 

 

log x

= y

x

= 10y

The basic base n logarithm:

 

 

 

lognx

= y

x

= ny

The basic natural logarithm (e is a constant with a value found near the start of this section:

ln x = loge x = y x = ey

Figure 34.6 Definitions of logarithms

• All logarithms observe a basic set of rules for their application,

logn( xy)

x logn -y

logn( xy)

logn( x)

ln ( A θ )

= logn( x) + logn( y)

logn( n) = 1

= logn( x) –logn( y)

logn( 1) = 0

 

= ylogn( x)

 

logm( x)

 

= ------------------

 

logm( n)

 

= ln ( A) + ( θ + 2π k) j

k I

Figure 34.7 Properties of logarithms

34.1.4 Polynomial Expansions

• Binomial expansion for polynomials,

math guide - 34.6

( a + x) n = an + nan – 1x + n-------------------( n – 1)

an – 2x2

+ … + xn

2!

 

 

Figure 34.8 A general expansion of a polynomial

34.1.5Practice Problems

1.Are the following expressions equivalent?

a)A( 5 + B) – C = 5A + B C

b)

A + B

A

+

B

C--------------+ D

= ---

D---

 

C

 

c)log ( ab) = log ( a) + log ( b)

d)5( 54) = 55

e)3log ( 4) = log ( 16)

f)( x + 6) ( x – 6) = x2 + 36

g)

10

log ( 5)

=

10

 

 

 

-----

 

 

 

( x + 1) 6

5

 

 

h)

= x

2

+ 2x + 1

------------------

 

 

( x + 1) 2

 

 

 

2.Simplify the following expressions.

a)x( x + 2) 2 – 3x

( x + 3) ( x + 1) x2

b)--------------------------------------

( x + 1) 2x

c)log ( x3) 64

d)-----

16

153

e)----- + -----

2128

f)( x2y3) 4

g)4x2 – 8y4

58

h)--3 --9

i)5

--4

-------

5

j)( y + 4) 3( y – 2)

k)x2y x + 1

l)----------- = 4 x + 2

math guide - 34.7

3. Simplify the following expressions.

a)A + B

-------------

AB

b) AB

-------------

A + B

c)( x4y5) 3

--------------

x2

d)log ( x5) + log ( x3)

(ans.

 

 

 

 

 

 

 

a)

A + B

=

A

B

1

1

 

-------------

------

+ ------- =

--

+ --

 

 

AB

 

AB

AB

B

A

b)

 

AB

 

 

 

 

 

 

-------------

cannot be simplified

 

A + B

c)

( x4y5) 3

2 5 3

 

6 15

 

 

--------------

=

( x y )

= x y

 

 

 

 

x2

 

 

 

 

 

d)

log ( x5) + log ( x3) =

5log ( x) + 3log ( x) = 8log ( x)

4. Simplify the following expressions.

a)nlog ( x2) + mlog ( x3) – log ( x4)

(ans.

a)nlog ( x2) + mlog ( x3) – log ( x4)

2nlog ( x) + 3mlog ( x) – 4log ( x) ( 2n + 3m – 4) log ( x)

( 2n + 3m – 4) log ( x)

= x + 2

math guide - 34.8

5. Rearrange the following equation so that only ‘y’ is on the left hand side.

y + x

-----------

y + z

(ans.

 

y + x

 

 

----------- = x + 2

 

 

y + z

 

 

y + x = ( x + 2) ( y + z)

 

 

y + x = xy + xz + 2y + 2z

 

 

y xy – 2y = xz + 2z x

 

 

y( – x – 1) = xz + 2z x

 

 

y

xz + 2z x

 

 

= -------------------------

 

 

 

x – 1

6. Find the limits below.

a)

 

 

t3 + 5

 

lim

 

 

 

 

----------------

 

t

0

5t3 + 1

 

 

 

t3 + 5

b)

lim

 

 

 

----------------

 

t

5t3 + 1

(ans.

t3 + 5

03 + 5

 

a)

lim

----------------

----------------------

= 5

=

5( 0) 3 + 1

 

t 0

5t3 + 1

 

b)

t3 + 5

 

3 + 5

 

3

 

 

lim

----------------

=

-----------------------

=

--------------

= 0.2

 

 

5( ∞ ) 3 + 1

5( ∞ ) 3

 

t → ∞

5t3 + 1