Robert Batzinger
Dec 2 17
Condition | Equivalent |
---|---|
Either you win the lottery or else you are not rich. | \( L \lor \lnot R \) |
Either you don’t win the lottery or else you are rich. | \( \lnot L \lor R \) |
You will win the lottery and be rich. | \( L \land R \) |
You will be rich if you win the lottery. | \( L \to R \) |
You will win the lottery if you are rich. | \( R \to L \) |
It is necessary for you to win the lottery to be rich. | \( L \to R \) |
It is sufficient to win the lottery to be rich. | \( L \to R \) |
You will be rich only if you win the lottery. | \( L \leftrightarrow R \) |
Unless you win the lottery, you won’t be rich. | \( L \leftrightarrow R \) |
If you are rich, you must have won the lottery. | \( L \to R \) |
If you are not rich, then you did not win the lottery. | \( \lnot R \to \lnot L \) |
You will win the lottery if and only if you are rich | \( R \leftrightarrow L \) |
\[ \]
Definitions: (0.3) - Notation, Relationships Between Sets, Operations On Sets, Venn Diagrams
Functions: (0.4) - Surjections, Injections, Bijections, Inverse
Counting: (1) - Additive and Multiplicative Principles: (1.1), Binomial Coefficients: (1.2)
Index to Activities
Index to Exercises:
\[ \]
This version cannot be drawn on a single plane without the edges intersecting
\tag
\begin{..} ... \end{..}
{...}
$$d = \sqrt{a_0^2 + a_1^2}$$
\vfil \hfil \bigskip \smallskip
\tiny \small \normalsize \large \huge
\bf \tt \sl \it
\section \subsection \subsubsection
\includegraphics{width=\columnwidth}{pic.png}
\begin{tabular}{lr} aa & 3.5\\ b & 17.2\\ \end{tabular}
\footnote{This is a note}
\cite{Knuth:1970}
\label{id} .. As seen in \ref{id}
\addresslabel[\fboxsep=5mm]{\vbox to 75mm{%
\hbox to 40mm{\kern-5pt
$\vcenter{\hbox to 1.7cm{%
\includegraphics[width=1.7cm]{payap.png}\hss}}\
\vcenter{\raggedright
Payap University\\ Faculty of Sci\\
Amphur Muang\\ Chiang Mai 50000\\
Thailand\\}$\hss}%
\vfill{\centering {\Large\scshape
\textbf{Dr.~Robert~P.~Batzinger}\\}\medskip
\textit{Instructor Emeritus}\\}
\vfill{\raggedleft \small
\textit{Office: \phonei}\\%
\textit{LinkedIn: robert-batzinger}\\%
\textit{Email: \emaili}\\}}}
A set is a collection of objects, which are called elements. The order of the elements does not matter, and each element may occur no more than once. An element may be atomic or molecular.
\[ \]
Notation | \( \LaTeX \) | Explanation |
---|---|---|
\( X = \{a,b,c\} \) | X = \{a,b,c\} |
\( X \) is a set that contains \( a,b,c \) |
\( Y = \{b,c,d\} \) | Y = \{b,c,d\} |
\( Y \) is a set that contains \( b,c,d \) |
\( Z = \{X, Y\} \) | Z = \{X, Y\} |
\( Z \) is a set of Sets \( X \) and \( Y \) |
\( A \subset X \) | A \subset X |
Set \( A \) is a subset of \( X \) |
\( B \subseteq X \) | B \subseteq X |
Set \( B \) is a subset or equals to Set \( X \) |
\( a \in X \) | a \in X |
\( a \) is an element of Set \( X \) |
\( d \not\in X \) | d \not\in X |
\( d \) is not an element of Set \( X \) |
\( \LaTeX \) | Definition | Explanation |
---|---|---|
\emptyset |
\( \emptyset \) | \( \emptyset \) is a set with no elements |
\mathbb{P} |
\( \mathbb{P} = \{2,3,5,7,11,...\} \) | \( \mathbb{P} \) is a set of Prime Numbers |
\mathbb{W} |
\( \mathbb{W} = \{1,2,3,4,...\} \) | \( \mathbb{W} \) is a set of Whole Numbers |
\mathbb{N} |
\( \mathbb{N} = \{0,1,2,3,4,...\} \) | \( \mathbb{N} \) is a set of Natural Numbers |
\mathbb{Z} |
\( \mathbb{Z} = \{...,-3,-2,-1,0,1,2,3,...\} \) | \( \mathbb{Z} \) is a set of all Integers |
\mathbb{Q} |
\( \mathbb{Q} = \{x \in \mathbb{R} : x = n/m : \forall n,m \in \mathbb{Z}\} \) | \( \mathbb{Q} \) is a set of all Rational Numbers |
\mathbb{R} |
\( -\infty < \mathbb{R} < \infty \) | \( \mathbb{R} \) is a set of all Real Numbers |
\cal U |
\( \cal U \) | Set of all elements in the domain |
\( \LaTeX \) | Notation | Description |
---|---|---|
\{ ,\} |
\( \{ ,\} \) | The elements of a set. \( \{1, 2, 3\} \) is the set containing 1, 2, and 3. |
: |
\( : \) | \( \{x : x > 2\} \) is the set of all \( x \) where \( x > 2 \) |
\in |
\( \in \) | \( 2 \in \{1, 2, 3\} \) asserts that \( 2 \) is an element of the set |
\not\in |
\( \not\in \) | \( 4 \not\in \{1,2,3\} \) asserts that \( 4 \) is not an element of the set |
{\cal P}(A) |
\( {\cal P}(A) \) | \( {\cal P}(A) \) is a power set of \( A \) containing all the subsets of \( A \) |
Please note which of these is true
Given \( A=\{1,2,3\}, X = {\cal P}(A): \)
\( \qquad\exists y \in X: y \subseteq A, y = A \)
Hint (What is the value of \( y \) ?)
Given \( A = \emptyset, X = {\cal P}(A):X = A \)
Hint: (What is the value of \( X \) ?)
Given \( A = \emptyset, X = ? \)\
\[ \]
Which are true, false, or meaningless?
Given \( A=\{1,2,3,4,5,6\}, \) \( B=\{2,4,6\}, \) \( C=\{1,2,3\}, \) and \( D=\{7,8,9\} \)
\[ \begin{array}{ll|ll} * & $A \subset B$ & * & $B \subset A$ \\ * & $B \in C$ & * & $A > D$ \\ * & $\emptyset \in A$ & * & $\emptyset \subset A$ \\ * & $3 \in C$ & * & $3 \subset C$ \\ * & $\{3\} \subset C$ & * & $\{3,3,2,1,1\} = C$ \\ \end{array} \]
\[ \]
Definition
Cardinality of a set equals the number of unique elements of a set.
\[ A = \{1,2,3\} \implies |A| = 3 \]
Find the cardinality of the following sets
\( \LaTeX \) | Math | Description |
---|---|---|
\subseteq |
\( \subseteq \) | \( A \subseteq B \) asserts that \( A \) is either a subset of \( B \) or \( A = B \). |
\subset |
\( \subset \) | \( A \subset B \) asserts that \( A \) is subset of \( B \): every element of \( A \) is also in \( B \) but \( A \neq B \). |
\cap |
\( \cap \) | \( A\cap B \) is the intersection of \( A \) and \( B \): elements existing in both \( A \) and \( B \). |
\cup |
\( \cup \) | \( A \cup B \) is the union of \( A \) and \( B \): all elements in either \( A \) or \( B \) or both |
\times |
\( \times \) | \( A \times B \) is a Cartesian product: the set of all pairs \( (a, b) \) with \( a \in A \) and \( b \in B \). |
\backslash |
\( \backslash \) | \( A\backslash B \) is Set \( A \) minus Set \( B \): all elements of \( A \) which are not elements of \( B \). |
\bar{A} |
\( \bar{A} \) | The complement of \( A \) is the set of everything except elements of \( A \) |
\( |A| \) | \( |A| \) | The cardinality of A is the number of elements in \( A \). |
\[ \small\begin{array}{|c|c|c|c|c|} \hline A & |A| & {\cal P}(A) & count({\cal P}(A)) & |{\cal P}(A)| \\ \hline \emptyset & 0 & \{\emptyset\} & (1) & 1 \\ \hline \{1\} & 1 & \{\{\emptyset\},\{1\}\} & (1+1) & 2 \\ \hline \{1,2\} & 2 & \{\{\emptyset\}, \{1\}, \{2\}, \{1,2\}\} & (1+2+1) & 4 \\ \hline \{1,2,3\} & 3 & \{\{\emptyset\}, \{1\}, \{2\}, \{3\}, \{1,2\}, \{1,3\}, \{2,3\}, \{1,2,3\}\} & (1+3+3+1) & 8 \\ \hline \{1,2,3,4\} & 4 & \{\{\emptyset\}, \{1\}, \{2\}, \{3\}, \{4\}, \{1,2\}, \{1,3\}, \{1,4\}, & (1+4+6+4+1) & 16 \\ & & \{2,3\}, \{2,4\}, \{3,4\}, \{1,2,3\}, \{1,2,4\}, &&\\ & & \{1,3,4\}, \{2,3,4\}, \{1,2,3,4\}\} & & \\ \hline \{1,2,3,4,5\} & 5 & \{\{\emptyset\}, \{1\}, \{2\}, \{3\}, \{4\}, \{5\}, \{1,2\}, \{1,3\}, \{1,4\}, \{1,5\}, &(1+5+10+10+5+1) & 32 \\ & & \{2,3\}, \{2,4\}, \{2,5\}, \{3,4\}, \{3,5\}, \{4,5\}, \{1,2,3\}, & & \\ & &\{1,2,4\}, \{1,2,5\}, \{1,3,4\}, \{1,3,5\}, \{1,4,5\}, \{2,3,4\}, & & \\ & & \{2,3,5\}, \{2,4,5\}, \{3,4,5\}, \{1,2,3,4\}, \{1,3,4,5\}, & & \\ & &\{1,2,4,5\}, \{1,2,3,5\}, \{2,3,4,5\}, \{1,2,3,4,5\}\}& & \\ \hline \end{array} \]
require 'set'
setA = Set.new(1..3);
setB = Set.new([2,3])
setC = Set.new([2,3,4]);
setU = Set.new(1..4)
puts <<endmsg
A:#{setA.inspect} B:#{setB.inspect}
C:#{setC.inspect}
B subset A: #{setB.subset?(setA)}
A superset B: #{setA.superset?(setB)}
A union B: #{setA.union(setC).inspect}
A intersect C: #{setA.intersection(setC).inspect}
A intersect C: #{(setA & setC).inspect}
A intersect C?:#{setA.intersect?(setC)}
A subtract C: #{setA.difference(setC)}
Complement(B): #{setU.subtract(setB).inspect}
Cardinality(A):#{setA.size}
4 member of C?:#{setC.include?(4)
endmsg
A:#<Set: {1, 2, 3}> B:#<Set: {2, 3}>
C:#<Set: {2, 3, 4}>
B subset A: true
A superset B: true
A union B: #<Set: {1, 2, 3, 4}>
A intersect C: #<Set: {2, 3}>
A intersect C: #<Set: {2, 3}>
A intersect C?: true
A subtract C: #<Set: {1}>
Complement(B): #<Set: {1, 4}>
Cardinality(A): 3
4 member of C?: true
\[ \]
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{venndiagram}
\usepackage{xcolor}
\begin{document}\Large
\begin{venndiagram3sets}[labelOnlyA={1},
labelOnlyB={2},labelOnlyC={3},
labelOnlyAB={4},labelOnlyAC={5},
labelOnlyBC={6},labelABC={7},
labelNotABC={8},shade=orange]
\fillACapB \fillBCapC \fillACapC
\end{venndiagram3sets}
\end{document}
Use the Venn.tex to create a PDF that displays the following
Upload the diagram to the Google Classroom
Determine set expressions required to fill each of the colored areas
\[ \begin{array}{ll|ll} * & Red - $A / (B \cup C)$ & * & Green \\ * & Yellow - $(A \cup B)/C$ & * & Cyan\\ * & Blue & * & Purple\\ * & White & * & Grey\\ \end{array} \]
Create a Venn Diagram in yEd to represent the relationships between these standard sets:
\[ \mathbb{N}, \mathbb{P}, \mathbb{Q}, \mathbb{R}, \mathbb{W}, \mathbb{Z} \]
Sets: Slide 35
Amy finds a present on her doorstep. She suspects it was left by either Rachel, Tess, or Nicol. She confronts each one.
Assume that the present-giver is lying and the other two individuals are telling the truth.
Who left Amy the present?
English Statement | Equivalent Statement |
---|---|
Not [All ducks like cookies] | There exists a duck who does not like cookies. |
\( \lnot \Big(\forall d: \heartsuit(d,c) \Big) \) | \( \exists d: \lnot \heartsuit(d,c) \) |
Not [some duck likes cookies]) | All ducks do not like cookies |
\( \lnot \Big(\exists d: \heartsuit(d,c) \Big) \) | \( \forall d: \lnot \heartsuit(d,c) \) |
All ducks and All geese do not love cookies | There does not exist any duck or geese that love cookies |
\( \forall d,g: \lnot \heartsuit(d,c) \land \lnot \heartsuit(g,c) \) | \( \lnot \exists g \lor \lnot\exists d: \heartsuit(d,c) \lor \heartsuit(g,c) \) |
Some ducks and some geese do not like cookies | Not all ducks and geese like cookies. |
\( \exists d \lor \exists g: \lnot \heartsuit(d,c) \lor \lnot \heartsuit(g,c) \) | \( \lnot\forall d \land \lnot \forall g: \heartsuit(d,c) \land \heartsuit(g,c) \) |
Sets: Slide 40
\[ \]
A function is a rule that assigns each input exactly one output.
Domain is the set of all possible inputs.
Range is the set of all possible outputs.
Given the following mappings, which would qualitfy as functions?
\[ \]
Surjection where the elements of the domain cover the full range of value in the range.
\[ f : \{1, 2, 3, 4, 5, 6\} \Rightarrow \{a,b,c\} \]
\[ \begin{array}{|c|c|c|c|c|c|c|} \hline Original\ domain & 1 & 2 & 3 & 4 & 5 & 6 \\ \hline Outcomes\ value & a & a & b & b & b & c \\ \hline \end{array} \]
Injection where the elements of the domain map to unique values in the range (No duplicates).
\[ f : \{1, 2, 3, 4, 5\} \Rightarrow \{a,b,c, d, e, f\} \]
\[ \begin{array}{|c|c|c|c|c|c|c|} \hline Original\ domain & 1 & 2 & 3 & 4 & 5 \\ \hline Outcomes\ value & e & c & b & d & a \\ \hline \end{array} \]
Bijection where the all elements of the domain map to unique values which cover the entire range.
\[ f : \{1, 2, 3, 4, 5, 6\} \Rightarrow \{a,b,c, d, e, f\} \]
\[ \begin{array}{|c|c|c|c|c|c|c|} \hline Original\ domain & 1 & 2 & 3 & 4 & 5 & 6\\ \hline Outcomes\ value & f & c & b & d & a & e\\ \hline \end{array} \]
\[ f : \{1, 2, 3, 4, 5, 6\} \Rightarrow \{a,b,c, d, e, f\} \]
\[ f : \{a,b,c, d, e, f\} \Rightarrow \{1, 2, 3, 4, 5, 6\} \]
\[ \]
In a group of 10 people, if everyone shakes hands with everyone else exactly once, how many handshakes took place?
If there are 10 people and 3 chairs, how many groups of 3 are possible?
How many ways can you distribute 10 cookies to 7 students?
The additive principle states that if event \( A \) can occur in \( m \) ways, and event \( B \) can occur in \( n \) disjoint ways, then the event \( A \cup B \) can occur in \( m + n \) ways.
For 2 sets: \( |A \cup B| = |A| + |B| - |A \cap B| \)
For 3 sets: \( \small|A \cup B \cup C| = |A| + |B| + |C| - |A \cap B| - |A \cap C| - |B \cap C| +|A \cap B \cap C| \)
For given sets \( A \) and \( B \), the set of all ordered pairs \( \{x,y\} \) where \( x \in A \) and \( y \in B \)
\[ \hbox{For}\ A = \{1,2,3\}\ \hbox{and}\ B = \{A,B,C,D\} \]
\[ A \times B= \left\{ \begin{array}{ccc} \{1,A\} & \{2,A\} & \{3,A\}\\ \{1,B\} & \{2,B\} & \{3,B\}\\ \{1,C\} & \{2,C\} & \{3,C\}\\ \{1,D\} & \{2,D\} & \{3,D\}\\ \end{array} \right\} \]
If event \( A \) can occur in \( m \) ways, and each possibility for \( A \) allows for exactly \( n \) ways for event \( B \), then the event \( A \cup B \) can occur in \( m \times n \) ways
For sets: \( |A \times B| = |A| \cdot |B| \)
# MULTIPLICATIVE
x = 0
for i in 1..10
for j in 1..10
for k in 1..10
x = x + 1
end
end
end
puts x
1000
# ADDITIVE
x = 0
for i in 1..10
x = x + 1
end
for j in 1..10
x = x + 1
end
for k in 1..10
x = x + 1
end
puts x
30
def try(n)
x = 0
for i in 1..n
for j in 1..i
for k in 1..j
x = x + 1
end
end
end
puts x
end
n | x | \( \sum_{x=1}^n\ x \) |
---|---|---|
1 | 1 | 1 |
2 | 4 | 3 |
3 | 10 | 6 |
4 | 20 | 10 |
5 | 35 | 15 |
6 | 56 | 21 |
7 | 84 | 28 |
8 | 120 | 36 |
9 | 165 | 45 |
10 | 220 | 55 |
\[ \small\begin{array}{cccc} \textbf{n} & \textbf{Sequence} &\textbf{Sum} &\textbf{Equiv}\\ \hline 1 & \small 1 & 1 & 1{(1+1)\over 2} \\ 2 & \small 1+2 & 3 & 2{(1+2)\over 2} \\ 3 & \small 1+2+3 & 6 & 3{(1+3)\over 2} \\ 4 & \small 1+2+3+4 & 10 & 4{(1+4)\over 2} \\ 5 & \small 1+2+3+4+5 & 15 & 5{(1+5)\over 2} \\ 6 & \small 1+2+3+4+5+6 & 21 & 6{(1+6)\over 2} \\ 7 & \small 1+2+3+4+5+6+7 & 28 & 7{(1+7)\over 2} \\ 8 & \small 1+2+3+4+5+6+7+8 & 36 & 8{(1+8)\over 2} \\ \hline \end{array} \]
\[ \begin{array}{rcc} count & = & \sum{\{1 .. n\}} + \sum{\{1 .. (n-1)\}} + ... + \{1\} \\ & = & {x(x+1)\over 2} + {(x-1)((x-1)+1)\over 2} + ... + 1 \\ & = & {x_n + x_n^2\over 2} + {x_{n-1} + x_{n-1}^2\over 2} + ... + {x_{1} + x_{1}^2\over 2}\\ & = & {\sum_{i=1}^{n}\ x_i + \sum_{i=1}^{n}\ x_i^2\over 2} \\ \end{array} \]
x = 0
for i in 1..10
for j in 1..10
x = x + 1
end
for k in 1..10
x = x + 1
end
end
puts x
x = 0
for i in 1..10
for j in 1..10
for k in 1..10
x = x + 1
end
end
x = x + 1
end
puts x
If \( N \) objects are placed in \( K \) boxes, then there is at least one box containing at least \( \lceil N/K \rceil \) objects.
Example:
Among 100 people, there are at least \( \lceil 100 / 12 \rceil = 9 \) who were born in the same month.
A drawer contains a dozen brown socks and a dozen black sock, all unmatched. A man takes socks out at random in the dark.
If there are five possible grades (i.e., A, B, C, D, F), what is the minimum number of students needed to Ensure that at least six students get the same grade.
Given a restaurant offers 8 appetizers and 14 entrées.
How many choices do you have if:
A palindrome is a string that is identical to the string in reverse order. How many bit strings of length \( n \) are palindromes?
How many licence plates can be made using either two letters followed by 4 digits or four letters followed by 2 digit is?
How many books can be identified using the 12 digit ISBN?
\[ |{\cal P}(A)| = 2^5 = 32 \]
\[ \left({|A|\over n!\ (|A| - n)!}\right) \]
\[ \small\begin{array}{|c|c|c|c|c|} \hline n=0 & n=1 & n=2 & n=3 & n=4 & n=5 \\ \hline \left({5\atop 0}\right) & \left({5\atop 1}\right) & \left({5\atop 2}\right) & \left({5\atop 3}\right) & \left({5\atop 4}\right) & \left({5\atop 5}\right) \\ \hline \left({5!\over 0!\ 5!}\right) & \left({5!\over 1!\ 4!}\right) & \left({5!\over 2!\ 3!}\right) & \left({5!\over 3!\ 2!}\right) & \left({5!\over 4!\ 1!}\right) & \left({5!\over 5!\ 0!}\right) \\ \hline {5\cdot4\cdot3\cdot2\cdot1\over (5\cdot4\cdot3\cdot2\cdot1)} & {5\cdot4\cdot3\cdot2\cdot1\over (1)(4\cdot3\cdot2\cdot1)} & {5\cdot4\cdot3\cdot2\cdot1\over (2\cdot1)(3\cdot2\cdot1)} & {5\cdot4\cdot3\cdot2\cdot1\over (3\cdot2\cdot1)(2\cdot1)} & {5\cdot4\cdot3\cdot2\cdot1\over (4\cdot3\cdot2\cdot1)(1)} & {5\cdot4\cdot3\cdot2\cdot1\over (5\cdot4\cdot3\cdot2\cdot1)} \\ \hline {1 \over 1} & {5 \over 1} & {5\cdot4 \over 2\cdot1} = {5\cdot2\over 1} & {5\cdot4\cdot3 \over 3\cdot2\cdot1} = {5\cdot 2\over 1} & {5 \over 1} & {1 \over 1}\\ \hline 1 & 5 & 10 & 10 & 5 & 1 \\ \hline \emptyset & \{1\}, & \{1,2\}, \{2,3\}, &\{1,2,3\}, \{2,3,4\}, & \{1,2,3,4\}, & \{1,2,3,4,5\}\\ & \{2\}, &\{3,4\}, \{4,5\},& \{3,4,5\}, \{1,2,4\}, & \{1,2,3,5\}, & \\ &\{3\}, & \{1,3\}, \{1,4\}, &\{2,3,5\}, \{1,2,5\}, & \{1,2,4,5\}, & \\ &\{4\}, &\{1,5\}, \{1,4\}, &\{1,3,4\}, \{1,3,5\},&\{1,3,4,5\},&\\ &\{5\} &\{2,5\}, \{1,5\} & \{1,4,5\}, \{2,4,5\} & \{2,3,4,5\} & \\ \hline 00000 & 10000, & 11000,01100, & 11100, 01110, & 11110, & 11111 \\ & 01000, & 00110, 00011, & 00111, 11010, & 11101, & \\ & 00100, & 10100, 10010, & 01101, 11001, & 11011, & \\ & 00010, & 10001, 10010, & 10110, 10101, & 10111, &\\ & 00001 & 01001, 10001 & 10011, 01011 & 01111 & \\ \hline \end{array} \]
\[ \small\begin{array}{|l|c|c|c|c|c|} \hline weight: & k=0 & k=1 & k=2 & k=3 & k=4 & k=5 \\ \hline B^5_k & 00000 & 10000, & 11000, 01100, & 11100, 01110, & 11110,& 11111 \\ & & 01000, & 00110, 00011, & 00111, 10110, & 11101, & \\ & & 00100, & 10100, 01010, & 01011, 10011, & 11011, & \\ & & 00010, & 00101, 10010, & 10101, 11001, & 10111, & \\ & & 00001 & 01001, 10001 & 11010, 01101 & 01111 & \\ \hline B^5_k& 1 & 5 & 10 & 10 & 5 & 1 \\ \hline \end{array} \]
Recursively break the problem down by imposing a value of the first digit of the unknown set and solving the problem for the resulting subsets:
\[ \{?????\}_{k=3} = 0\{????\}_{k=3} + 1\{????\}_{k=2} \]
Once the problem has been reduced to a simple subset, the values are back substituted.
\[ \begin{array}{rcccccl} |B^5_3| & = & |B^4_3| + |B^4_2| &=& 4 + 6 & = & 10 \\ |B^4_3| & = & |B^3_3| + |B^3_2| &=& 1 + 3 & = & 4 \\ |B^4_2| & = & |B^3_2| + |B^3_1| &=& 3 + 3 & = & 6 \\ \end{array} \]
\[ \begin{array}{c} (x + y)^1 = x + y\\ (x + y)^2 = x^2 + 2xy + y^2\\ (x + y)^3 = x^3 + 3x^2y + 3xy^2 + y^3\\ (x + y)^4 = x^4 + +4x^3y + 6x^2y^2 + 4xy^3 + y^4\\ (x + y)^5 = x^5 + 5x^4y + 10x^3y^2 + 10x^2y^3 + 5xy^4 + y^5\\ \end{array} \]
\[ \begin{array}{c} \exists n,k: n \ge 0, 0 \le k \le n \Rightarrow\\ \left({n \atop k}\right)\\ \end{array} \]
n choose k
. \[ \left({n \atop k}\right) =\left({n-1 \atop k-1}\right) + \left({n-1 \atop k}\right) \]
Define these terms: