Elementary Algebra and Geometry - CRC Press Online Binomial Theorem For positive integer n, ()! ()! xy xn xy nn xy nn n xy nxy nn nn n n += ++-+--+ +---12 2 33 1 2 12 3 ˜-1+ yn. pqzshieNbsbmbzmpssbodt

1

1Elementary Algebra and Geometry

1.1 Fundamental Properties (Real Numbers)

a + b = b + a Commutative Law for Addition

(a + b) + c = a + (b + c) Associative Law for Addition

a + 0 = 0 + a Identity Law for Addition

a + (−a) = (−a) + a = 0 Inverse Law for Addition

a(bc) = (ab)c Associative Law for Multiplication

aa a

a a1 1

1 0æèç

öø÷ = æ

èç

öø÷ = ¹, Inverse Law for

Multiplication

(a)(1) = (1)(a) = a Identity Law for Multiplication

Copyrighted Material - Taylor & Francis

2 Integrals and Mathematical Formulas

ab = ba Commutative Law for Multiplication

a(b + c) = ab + ac Distributive Law

Division by zero is not defined.

1.2 Exponents

For integers m and n,

a a a

a a a

a a

ab a b

a b a b

n m n m

n m n m

n m nm

m m m

m m m

=

=

=

=

=

+

-/

/ /

( )

( )

( )

1.3 Fractional Exponents

a ap q q p/ /( )= 1

where a1/q is the positive qth root of a if a > 0 and the negative qth root of a if a is negative and q is odd. Accordingly, the five rules of exponents given above (for integers) are also valid if m and n are fractions, provided a and b are positive.



1.4 Irrational Exponents

If an exponent is irrational, e.g., 2 , the quantity, such as a 2 , is the limit of the sequence a1.4, a1.41, a1.414, ….

• Operations with Zero

0 0 10m a= =;

1.5 Logarithms

If x, y, and b are positive and b ≠ 1,

log log log

log / log log

log log

log

b b b

b b b

bp

b

b

xy x y

x y x y

x p x

( )

( )

= +

= -

=

(( )

.log

1

1

1 0

/ log

log

log :

x x

b

Note b x

b

b

bxb

= -

=

= =

• Change of Base (a ≠ 1)

log log logb a bx x a=



1.6 Factorials

The factorial of a positive integer n is the product of all the positive integers less than or equal to the integer n and is denoted n! Thus,

n n! .= × × ×¼×1 2 3

Factorial 0 is defined 0! = 1.

• Stirling’s Approximation

lim /n

nn e n n®¥

=( ) !2p

(See also Section 9.2.)

1.7 Binomial Theorem

For positive integer n,

( )( )

!

( )( )!

x y x nx yn n

x y

n n nx y

nxy

n n n n

n

n

+ = + + -

+ - - +

+

- -

-

1 2 2

3 3

12

1 23

�

-- +1 yn.



1.8 Factors and Expansion

( )

( )

( )

(

a b

a b

a b

a b

a ab b

a ab b

a a b ab b

+ =

- = -

+ =

-

+ +

+

+ + +

2

2

3

2 2

2 2

3 2 2 3

2

2

3 3

))

( ) ( )( )

( ) ( )(

3

2 2

3 3 2

3 2 2 33 3= - -

- = - +

- = - + +

+a a b ab b

a b a b a b

a b a b a ab b22

3 3 2 2

)

( ) ( )( )a b a b a ab b+ = + - +

1.9 Progression

An arithmetic progression is a sequence in which the difference between any term and the preced-ing term is a constant (d):

a a d a d a n d, , , , ( ) .+ + + -2 1…

If the last term is denoted l[= a + (n−1)d], then the sum is

s

na l= +

2( ).



A geometric progression is a sequence in which the ratio of any term to the preceding terms is a con-stant r. Thus, for n terms,

a ar ar arn, , ,,2 1… -

The sum is

S

a arr

n

= --1

1.10 Complex Numbers

A complex number is an ordered pair of real numbers (a, b).

Equality: (a, b) = (c, d) if and only if a = c and b = d

Addition: (a, b) + (c, d) = (a + c, b + d)

Multiplication: (a, b)(c, d) = (ac −.bd, ad + bc)

The first element of (a, b) is called the real part; the second, the imaginary part. An alternate notation for (a, b) is a + bi, where i2 = (−1, 0), and i(0, 1) or 0 + 1i is written for this complex number as a con-venience. With this understanding, i behaves as a number, i.e., (2 −.3i)(4 + i) = 8 −.12i + 2i −.3i2 = 11 −.10i. The conjugate of a + bi is a −.bi, and the product of a complex number and its conjugate is a2 + b2.



Thus, quotients are computed by multiplying numerator and denominator by the conjugate of the denominator, as illustrated below:

2 34 2

4 2 2 34 2 4 2

14 820

7 410

++

=- +- +

=+

=+i

ii ii i

i i( )( )( )( )

1.11 Polar Form

The complex number x + iy may be represented by a plane vector with components x and y:

x iy r i+ = +( )cos sinq q

(see Figure 1.1). Then, given two complex num-bers z1 = r1(cosθ1 + i sinθ1) and z2 = r2(cosθ2 + i sinθ2), the product and quotient are:

Product: z1z2 = r1r2[cos(θ1 + θ2) + i sin(θ1 + θ2)]

Quotient: z z r r i1 2 1 2 1 2 1 2/ / cos sin= - + -( )[ ( ) ( )]q q q q

Powers: z r i

r n i n

n n

n

= +( )éë ùû= +éë ùû

cos sin

sin

q q

q qcos

Roots: z r i

rkn

ikn

n

n

1 1

1 360 360

/ /

/

cos sin

. .

= +( )éë ùû

= + + +éëê

ù

q q

q q

n

cos sinûûú

= ¼

,

, , , ,k 0 1 2 1n -



1.12 Permutations

A permutation is an ordered arrangement (sequence) of all or part of a set of objects. The number of permutations of n objects taken r at a time is

p n r n n n n r

nn r

( , ) ( )( ) ( )

!( )!

= - - - +

=-

1 2 1�

A permutation of positive integers is even or odd if the total number of inversions is an even

0x

y

r

P (x, y)

θ

FIGURE 1.1Polar form of complex number.



integer or an odd integer, respectively. Inversions are counted relative to each integer j in the per-mutation by counting the number of integers that follow j and are less than j. These are summed to give the total number of inversions. For example, the permutation 4132 has four inversions: three relative to 4 and one relative to 3. This permuta-tion is therefore even.

1.13 Combinations

A combination is a selection of one or more objects from among a set of objects regardless of order. The number of combinations of n different objects taken r at a time is

C n r

P n rr

nr n r

( , )( , )

!!

!( )!= =

-

1.14 Algebraic Equations

• QuadraticIf ax2 + bx + c = 0, and a ≠ 0, then roots are

x

b b aca

= - ± -2 42



• CubicTo solve x3 + bx2 + cx + d = 0, let x = y −.b/3. Then the reduced cubic is obtained:

y py q3 0+ + =

where p = c − (1/3)b2 and q = d − (1/3)bc + (2/27)b3. Solutions of the original cubic are then in terms of the reduced cubic roots y1, y2, y3:

x y b x y b

x y b

1 1 2 2

3 3

1 3 1 3

1 3

= - = -

= -

( ) ( )

( )

/ /

/

The three roots of the reduced cubic are

y A B

y W A W B

y W A W B

11 3 1 3

21 3 2 1 3

32 1 3 1 3

= +

= +

= +

( ) ( )

( ) ( )

( ) ( )

/ /

/ /

/ /

where

A q p q= - + +1

21 27

14

3 2( ) ,/

B q p q= - - +1

21 27

14

3 2( ) ,/

W

iW

i= - + = - -1 32

1 32

2, .



When (1/27)p3 + (1/4)p2 is negative, A is complex; in this case, A should be expressed in trigono-metric form: A = r(cos θ + i sin θ), where θ is a first or second quadrant angle, as q is negative or positive. The three roots of the reduced cubic are

y r

y r

y r

11 3

21 3

1 3

2 3

23

120

23

= ( )

= ( ) + °æèç

öø÷

= ( )

/

/

/

( )cos /

cos

cos

q

q

q ++ °æèç

öø÷240

1.15 Geometry

Figures 1.2 through 1.12 are a collection of com-mon geometric figures. Area (A), volume (V), and other measurable features are indicated.

b

h

FIGURE 1.2Rectangle. A = bh.



b

h

FIGURE 1.3Parallelogram. A = bh.

h

b

FIGURE 1.4

Triangle. A bh=12

.

b

a

h

FIGURE 1.5

Trapezoid. A a b h= +12

( ) .



SR

θ

FIGURE 1.6Circle. A = πR2; circumference = 2πR; arc length S = Rθ (θ in radians).

θ

R

FIGURE 1.7

Sector of circle. A R A Rsector segment sin= = ( )12

12

2 2q q - q; .

R b

θ

FIGURE 1.8

Regular polygon of n sides. An

bn

Rb

n= =

4 22ctn csc

p p; .



h

R

FIGURE 1.9Right circular cylinder. V = πR2h; lateral surface area = 2πRh.

h

A

FIGURE 1.10Cylinder (or prism) with parallel bases. V = Ah.



R

FIGURE 1.12

Sphere. V R=43

3p ; surface area = 4πR2.

R

lh

FIGURE 1.11

Right circular cone. V R h=13

2p ; lateral surface area =

p pRl R R h= +2 2 .



1.16 Pythagorean Theorem

For any right triangle with perpendicular sides a and b, the hypotenuse c is related by the formula

c2 = a2 + b2

This famous result is central to many geometric relations, e.g., see Section 4.2.


Documents

Elementary Algebra and Geometry - CRC Press Online Binomial Theorem For positive integer n, ()! ()! xy xn xy nn xy nn n xy nxy nn nn n n += ++-+--+ +---12 2 33 1 2 12 3 ˜-1+ yn. pqzshieNbsbmbzmpssbodt