Sets and Number Systems
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The equation (A∩B)∪(A – B) = A is proven using properties like the ______ property.

distributive

The set of ______ numbers, denoted by N, includes the numbers 1, 2, 3, and so on.

natural

The set of ______, denoted by Z, includes all positive and negative whole numbers, as well as zero.

integers

The set of positive integers, denoted by Z+, is equivalent to the set of ______ numbers.

<p>natural</p> Signup and view all the answers

The set of ______ numbers, denoted by Q, includes numbers that can be expressed as a fraction a/b, where a and b are integers and b ≠ 0.

<p>rational</p> Signup and view all the answers

A decimal representation of a rational number is either terminating or ______.

<p>repeating</p> Signup and view all the answers

To express the repeating decimal 4.83 as a rational number, you can set x = 4.83 and then find expressions for 10x and ______ to eliminate the repeating part.

<p>100x</p> Signup and view all the answers

In the proof (A∩B)∪(A – B) = A ∩(A∪Bʹ), the step (A∪Bʹ)∩U = A∪Bʹ is justified because any set intersected with the ______ set remains unchanged.

<p>universal</p> Signup and view all the answers

The set difference A – B is defined as the set of all elements $x$ such that $x$ is in A and $x$ is not in ______.

<p>B</p> Signup and view all the answers

If U is the universal set, the ______ of a set A, denoted by A', contains all elements in U that are not in A.

<p>complement</p> Signup and view all the answers

A ______ diagram is a pictorial representation of sets, often using circles within a rectangle to represent the universal set.

<p>Venn</p> Signup and view all the answers

The ______ of two sets A and B, denoted A ∩ B, includes all elements that are present in both A and B.

<p>intersection</p> Signup and view all the answers

Two sets A and B are considered ______ if their intersection results in an empty set (A ∩ B = ∅).

<p>disjoint</p> Signup and view all the answers

The ______ of two sets A and B, denoted A ∪ B, encompasses all elements found in either A or B, or both.

<p>union</p> Signup and view all the answers

According to De Morgan's Laws, the complement of the union of two sets (A ∪ B)' is equal to the intersection of their individual ______ A' ∩ B'.

<p>complements</p> Signup and view all the answers

If set B is a subset of set A (B ⊂ A), it logically follows that the complement of A (A') is a subset of the ______ of B (B').

<p>complement</p> Signup and view all the answers

The proof that $\sqrt{2}$ is not a rational number relies on making an ______ about $\sqrt{2}$ and showing that this leads to contradictory statements.

<p>assumption</p> Signup and view all the answers

If $m^2$ has a factor of 2, then $m^2$ is ______, which implies that $m$ itself must be divisible by 2.

<p>even</p> Signup and view all the answers

To show that $\sqrt{2} + \sqrt{3}$ is not a rational number, one begins by supposing that $\sqrt{2} + \sqrt{3}$ is ______ and manipulates the equation to arrive at a contradiction.

<p>rational</p> Signup and view all the answers

A ______ number is defined as one that can be expressed as a quotient of two integers.

<p>rational</p> Signup and view all the answers

An irrational number, such as $\pi$ or $\sqrt{2}$, cannot be expressed as a simple ______ of two integers.

<p>quotient</p> Signup and view all the answers

The union of the the set of ______ numbers with the set of irrational numbers creates the set of real numbers, denoted as R.

<p>rational</p> Signup and view all the answers

The set of real numbers contains the set of natural numbers and the set of ______.

<p>integers</p> Signup and view all the answers

When representing intervals on the real number line, a ______ bracket, such as ( or ), indicates that the number at the boundary is not included in the interval.

<p>open</p> Signup and view all the answers

To eliminate the decimal part when converting a repeating decimal to a fraction, subtracting 100x minus 10x from $435.87$ results in 90x = ______.

<p>435</p> Signup and view all the answers

When converting $0.354$ (with the 354 repeating) to a fraction, setting $x = 0.354$ implies $1000x = 354.354$, and subtracting $1000x - x$ isolates the repeating part, giving 999x = ______.

<p>354</p> Signup and view all the answers

To demonstrate that $2.75$ is a rational number, multiplying by a suitable power of 10 removes the decimal, so $100x = 275$, thus $x = 275/100$ which simplifies to ______.

<p>11/4</p> Signup and view all the answers

An irrational number is defined as a number that cannot be expressed in the form a/b for any integers a and b, and its decimal representation is non-terminating and ______.

<p>non-repeating</p> Signup and view all the answers

If $p^2$ is divisible by 2, then the proof by contradiction demonstrates that $p$ itself must be ______ by 2.

<p>divisible</p> Signup and view all the answers

In a proof by ______, one assumes the opposite of what needs to be proven. This assumption is then followed to a logical, yet contradictory, conclusion, thereby affirming the original statement.

<p>contradiction</p> Signup and view all the answers

To prove that $\sqrt{2}$ is not a rational number, one starts by assuming that it ______ can be expressed as a fraction a/b, where a and b are integers.

<p>can</p> Signup and view all the answers

When expressing a repeating decimal as a fraction, the goal is to eliminate the repeating part through a process that often involves ______ and subtraction, hence simplifying the number into a rational form.

<p>multiplication</p> Signup and view all the answers

The ________ law states that for any real numbers a, b, the sum a + b is always equal to b + a.

<p>commutative</p> Signup and view all the answers

According to the ________ law of addition, the way in which numbers are grouped does not change their sum: a + (b + c) = (a + b) + c.

<p>associative</p> Signup and view all the answers

The ________ identity states that for any real number 'a', a + 0 = a. Here, adding zero does not change the original value.

<p>additive</p> Signup and view all the answers

The ________ identity property is demonstrated when any real number 'a' is multiplied by 1, resulting in 'a': a * 1 = a.

<p>multiplicative</p> Signup and view all the answers

Every real number 'a' has an ________ inverse '-a' such that a + (-a) = 0, illustrating the concept of balancing values to reach zero.

<p>additive</p> Signup and view all the answers

The ________ law, a(b + c) = ab + ac, shows how to distribute a single term across multiple terms inside parentheses, simplifying expressions.

<p>distributive</p> Signup and view all the answers

The ________ property posits that for any two real numbers x and y, only one of the following is true: x > y, x < y, or x = y.

<p>trichotomy</p> Signup and view all the answers

In solving the linear equation $ax + b = c$, by adding $(-b)$ to both sides we get $ax = c - b$. This step uses the property of the ________ inverse.

<p>additive</p> Signup and view all the answers

When adding complex numbers $(3 + 5i)$ and $(2 - 3i)$, we add the real and ______ parts separately to get $5 + 2i$.

<p>imaginary</p> Signup and view all the answers

To simplify $(4 + i)^2$, we expand it as $(4 + i)(4 + i)$, which equals $16 + 8i + i^2$. Then, knowing that $i^2 = -1$, we find that $(4 + i)^2$ simplifies to ______ + 8i.

<p>15</p> Signup and view all the answers

When dividing complex numbers, for example $\frac{2 - 5i}{3 + 2i}$, we multiply both the numerator and the denominator by the ______ of the denominator.

<p>conjugate</p> Signup and view all the answers

If $z = \frac{3 + 2i}{4 - 3i}$, to express $z$ in the form $a + ib$, we multiply the numerator and denominator by the conjugate of the denominator, which simplifies to $z = \frac{6}{25} + \frac{17}{25}i$. Therefore, the real part, $a$, of $z$ is ______.

<p>6/25</p> Signup and view all the answers

Given $z = \frac{3 + 2i}{4 - 3i}$, after expressing it in the form $a + bi$ and finding $a$ and $b$, the magnitude squared of $z$, denoted as $|z|^2$, is calculated as $a^2 + b^2$. Thus, $|z|^2$ equals ______.

<p>13/25</p> Signup and view all the answers

To solve for $x$ and $y$ in the equation $\frac{x + iy}{2 + i} = 3 - 5i$, we cross-multiply to get $x + iy = (3 - 5i)(2 + i)$. After expanding and simplifying, we equate the real and imaginary parts to find that $x$ equals ______.

<p>11</p> Signup and view all the answers

Given the equation $\frac{1}{x + iy} = \frac{3 - 2i}{1 + i}$, to find $x$ and $y$, we cross-multiply to obtain $1 + i = (3 - 2i)(x + iy)$. After expanding the right side and equating real and imaginary parts, we can solve for $x$ and $y$, assuming that $x + iy$ is not equal to ______

<p>0</p> Signup and view all the answers

In the expression $\frac{2 - 5i}{3 + 2i}$, multiplying the numerator and denominator by $3 - 2i$ is a strategic step because it eliminates the ______ part from the denominator.

<p>imaginary</p> Signup and view all the answers

Flashcards

Set Difference

A – B = {x ⏐ x ∈ A and x ∉ B} shows elements in A but not in B.

Complement of a Set

Aʹ = U – A contains all elements in the universal set not in A.

Venn Diagram

A pictorial representation to show relationships between sets, like subsets and overlaps.

Set Intersection

A∩B = {x ⏐ x ∈ A and x ∈ B} is the set of elements common to both A and B.

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Disjoint Sets

A and B are disjoint if A∩B = ∅; they share no common elements.

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Set Union

A∪B = {x ⏐ x ∈ A or x ∈ B} combines all elements from both A and B.

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Properties of Set Operations

Commutativity, Associativity, Distributive Properties govern how sets interact.

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De Morgan's Laws

(A ∪ B)ʹ = Aʹ ∩ Bʹ and (A ∩ B)ʹ = Aʹ ∪ Bʹ show relations between complements and unions/intersections.

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Rational Numbers

Set of numbers in the form a/b, where a and b are integers, b ≠ 0.

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Decimal Representation of Rational Numbers

Rational numbers can be terminating or repeating decimals.

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Terminating Decimal

A decimal that ends after a finite number of digits, like 0.5.

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Repeating Decimal

A decimal where one or more digits repeat indefinitely, like 0.333...

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Set of Natural Numbers (N)

The set of positive integers: N = {1, 2, 3, ...}.

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Set of Integers (Z)

Includes all positive and negative whole numbers, plus zero: Z = {..., -3, -2, -1, 0, 1, 2, 3, ...}.

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Set of Real Numbers (R)

Includes all rational and irrational numbers; forms the basis of calculus.

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Set of Positive Integers (Z+)

Same as the set of natural numbers: Z+ = N = {1, 2, 3, ...}.

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Irrational Number

A number that cannot be expressed as a fraction a/b; its decimal form is non-terminating and non-repeating.

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Non-Terminating Decimal

A decimal that continues forever without repeating, e.g., π.

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Proof by Contradiction

A method where you assume the opposite of what you want to prove, find a conflict, showing the assumption is false.

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Power of 10 Multiplication

Multiplying by powers of 10 shifts the decimal point, helping to eliminate decimals.

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2.75 as a Fraction

2.75 is expressed as a fraction: 275/100 = 11/4.

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Square of an Integer

If p is an integer and p² is even, then p itself must also be even.

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Commutative Law

a + b = b + a and ab = ba; order of addition/multiplication doesn't matter.

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Associative Law

a + (b + c) = (a + b) + c; grouping of numbers doesn't affect sum/product.

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Additive Identity

The real number 0 is additive identity: a + 0 = a.

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Multiplicative Identity

The real number 1 is multiplicative identity: a * 1 = a.

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Additive Inverse

For each a ∈ R, there exists -a such that a + (-a) = 0.

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Multiplicative Inverse

Each nonzero real number a has an inverse 1/a such that a * (1/a) = 1.

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Distributive Law

a(b + c) = ab + ac; multiplication distributes over addition.

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Trichotomy Law

For any x, y ∈ R, either x > y, x < y, or x = y.

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Even Number

An integer divisible by 2 without a remainder.

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Set of Real Numbers

The union of rational and irrational numbers.

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Continuous Line

Real numbers form a line that cannot be counted.

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Intervals

A range of numbers represented with brackets for boundaries.

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Contradiction Example

The case where 2 + 3 yields irrational results despite rational assumption.

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Adding Complex Numbers

Combine real parts and imaginary parts separately.

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Complex Multiplication

Multiply norms and add angles in complex numbers.

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i Squared

i² = -1, fundamental property of imaginary units.

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Finding the Modulus

|z| = √(a² + b²) for z = a + bi.

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Conjugate of a Complex Number

If z = a + bi, then conjugate is a - bi.

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Cross-Multiplication with Complex Numbers

Multiply both sides by the denominator's conjugate.

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Real and Imaginary Parts

Atoms of the complex number z = a + bi are a (real) and b (imaginary).

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Equating Complex Numbers

Set real parts equal and imaginary parts equal.

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Study Notes

Sets Operations

  • A set is a collection of well-defined objects called elements. Elements within a set must be distinct and distinguishable.
  • Capital letters are used for set names and lowercase letters for set elements.
  • Braces {} are used to represent sets; elements are listed between the braces, e.g., A = {1, 2, 3, 4}.
  • Sets can also be described by defining a property or attribute, e.g., A = {x : x is a natural number}.
  • x ∈ A means 'x belongs to A'.
  • x ∉ A means 'x does not belong to A'.

Set Notation

  • A = {2, 3, 4, 5, 6} , A = {n : n is a natural number and 1 < n < 7}
  • A = {2, 4, 6, 8, 10} 4 ∈ A, 5 ∉ A.
  • S = {1, 2, 3, 4, 10} and B = {k ∈ S : k = 3n + 1, n = 0, 1, 2, 3}, B = {1, 4, 7, 10}.
  • A ⊆ B or B ⊃ A means 'A is a subset of B'. Every element in A is also in B.
  • A = B, if both A ⊆ B and B ⊆ A.
  • Ø denotes the empty set (null set) i.e., a set with no elements. The empty set is a subset of every set.

Set Operations

  • Intersection (A∩B) is the set containing common elements of sets A and B. A∩B = {x | x ∈ A and x ∈ B}.
  • Union (A∪B) is the set of all elements that belong to either set A or set B or both. A∪B = {x | x∈ A or x ∈ B}.
  • Disjoint sets: A and B are disjoint if their intersection is the empty set (A∩B = Ø).
  • Difference (A − B) contains elements in A but not in B; A − B = {x | x ∈ A and x ∉ B}.
  • Complement (A'): The complement of A, written A', is the set of all elements in the universal set U that are not in A; A' = U – A.
  • Venn diagram: A visual representation of sets.
  • Commutativity: A∪B = B∪A; A∩B = B∩A.
  • Associativity: AU(B∪C) = (A∪B)∪C; A∩(B∩C) = (A∩B)∩C.

Distributive properties

  • A ∩ (B∪C) = (A∩B) ∪ (A∩C)
  • A ∪ (B∩C) = (A∪B) ∩ (A∪C)

De Morgan's Laws

  • (A ∪ B)' = A' ∩ B'
  • (A ∩ B)' = A' ∪ B'

Sets of Numbers

  • Natural numbers (N): {1, 2, 3, ...}
  • Integers (Z): {..., -3, -2, -1, 0, 1, 2, 3, ...}
  • Rational numbers (Q): numbers that can be expressed as a fraction a/b, where a and b are integers and b ≠ 0.
  • Irrational numbers (Irr): numbers that cannot be expressed as a fraction of integers.
  • Real numbers (R): the union of rational and irrational numbers.
  • Intervals: a subset of real numbers
  • The real numbers R form a continuous line.
  • Intervals can be represented using brackets: open brackets ( ) for excluding endpoints, closed brackets [ ] for including endpoints.

Properties of Real Numbers

  • Commutative law of addition: a + b = b + a
  • Commutative law of multiplication: ab = ba
  • Associative law of addition: a + (b + c) = (a + b) + c
  • Associative law of multiplication: a(bc) = (ab)c
  • Additive identity: a + 0 = a
  • Multiplicative identity: a × 1 = a

Order Relations

  • x > y if x − y > 0 (x is greater than y)
  • x < y if x − y < 0 (x is less than y)
  • x = y if x − y = 0 (x is equal to y)

Absolute Value

  • |x| = x if x ≥ 0
  • |-x| = x if x < 0

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Questions cover set theory, including operations like union, intersection, and set difference. It also covers number systems such as natural, integer, rational, and real numbers, along with their properties and representations.

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