Relations and Functions in Mathematics

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Questions and Answers

Which characteristics does relation R = {(1, 2), (2, 2), (1, 1), (4, 4), (1, 3), (3, 3), (3, 2)} exhibit?

  • R is reflexive and symmetric but not transitive.
  • R is symmetric and transitive but not reflexive.
  • R is reflexive and transitive but not symmetric. (correct)
  • R is an equivalence relation.

Which pair belongs to the relation R = {(a, b) : a = b - 2, b > 6}?

  • (2, 4) ∈ R
  • (3, 8) ∈ R (correct)
  • (8, 7) ∈ R
  • (6, 8) ∈ R

What type of function is defined by the relation R = {(x, x) : x ∈ ℝ}?

  • Rational function
  • Identity function (correct)
  • Modulus function
  • Polynomial function

Which operation is NOT typically used for combining functions?

<p>Concatenation (C)</p> Signup and view all the answers

Which of the following statements about relations is correct?

<p>All equivalence relations are reflexive, symmetric, and transitive. (A)</p> Signup and view all the answers

What is the principal value of $sin^{-1}(-\frac{1}{2})$?

<p>-\frac{\pi}{6} (A)</p> Signup and view all the answers

What is the principal value of $cos^{-1}(\frac{\sqrt{3}}{2})$?

<p>60 (A)</p> Signup and view all the answers

What is the principal value of $cosec^{-1}(2)$?

<p>60 (A)</p> Signup and view all the answers

What is the principal value of $tan^{-1}(-\sqrt{3})$?

<p>-60 (B)</p> Signup and view all the answers

Which of the following statements describes the relation R = {(x, y): 3x - y = 0} in set A = {1, 2, 3,..., 14}?

<p>It is reflexive, symmetric, and transitive. (B)</p> Signup and view all the answers

For the relation R = {(x, y): y = x + 5 and x < 4} defined in the set of natural numbers, which is true?

<p>It is neither reflexive nor symmetric. (A)</p> Signup and view all the answers

What classification does the relation R = {(a, b): a ≤ b²} in the set of real numbers fall into?

<p>Neither reflexive, nor symmetric, nor transitive. (A)</p> Signup and view all the answers

The relation R = {(a, b): b = a + 1} defined in the set {1, 2, 3, 4, 5, 6} is classified as:

<p>Transitive but not reflexive or symmetric. (D)</p> Signup and view all the answers

Which of these relations defined in set of integers is described as not symmetric?

<p>R = {(x, y): x is wife of y} (C)</p> Signup and view all the answers

Is the function $f: ext{R}^* \rightarrow \text{R}^*$ defined by $f(x) = \frac{1}{x}$ one-to-one?

<p>Yes, for all values of x in $ ext{R}^*$ (D)</p> Signup and view all the answers

What happens to the injectivity of the function $f: ext{N} \rightarrow ext{N}$ defined by $f(x) = x^2$?

<p>It is not injective as it maps different inputs to the same output (B)</p> Signup and view all the answers

Is the function $f: ext{R} \rightarrow ext{R}$ given by $f(x) = [x]$ onto?

<p>No, it cannot achieve any real number that is not an integer (B)</p> Signup and view all the answers

For the function $f: ext{Z} \rightarrow ext{Z}$ defined by $f(x) = x^2$, what can be said about its surjectivity?

<p>It is not surjective because negative integers cannot be achieved (D)</p> Signup and view all the answers

What is true about the function $f: ext{N} \rightarrow ext{N}$ defined by $f(x) = x^3$?

<p>It is both injective and surjective (C)</p> Signup and view all the answers

What is the characterization of the modulus function $f(x) = |x|$ in terms of injectivity and surjectivity?

<p>It is neither one-one nor onto. (A)</p> Signup and view all the answers

Which statement about the signum function $f(x)$ is true?

<p>It can map multiple inputs to the same output. (B)</p> Signup and view all the answers

For the function $f: R ightarrow R$ defined by $f(x) = 1 + x^2$, which property does it exhibit?

<p>It is one-one but not onto. (B)</p> Signup and view all the answers

What is the range of y if sin⁻¹(x) = y?

<p>0 ≤ y ≤ π (C)</p> Signup and view all the answers

Is the function $f: N ightarrow N$ defined by $f(n) = rac{n+1}{2}$ if $n$ is odd and $f(n) = rac{n}{2}$ if $n$ is even a bijective function?

<p>No, it is many-one. (A)</p> Signup and view all the answers

What is the result of the expression tan⁻¹(√3) - sec⁻¹(-2)?

<p>2π/3 (A)</p> Signup and view all the answers

For the function $f: A ightarrow B$ defined by $f(x) = \frac{x-3}{x-1}$ with $A = R - {3}$ and $B = R - {1}$, is it one-one and onto?

<p>Yes, it is both one-one and onto. (A)</p> Signup and view all the answers

What is the value of cos⁻¹(1/√2)?

<p>π/4 (C)</p> Signup and view all the answers

What is the result of the expression cot⁻¹(√3)?

<p>π/3 (C)</p> Signup and view all the answers

How can you express the sum cos⁻¹(1/2) + 2 sin⁻¹(1/2)?

<p>π/2 (A)</p> Signup and view all the answers

What is the simplest form of $\tan^{-1} \frac{\cos x - \sin x}{\cos x + \sin x}$?

<p>$\frac{\pi}{4} - x$ (A)</p> Signup and view all the answers

For $\tan^{-1} \frac{x}{\sqrt{a^2 - x^2}}$, what is the simplest interpretation when $0 < x < a$?

<p>$\sin^{-1}(\frac{x}{a})$ (B)</p> Signup and view all the answers

What is the correct relation for $\tan^{-1}(\frac{1 - \cos x}{1 + \cos x})$ for $0 < x < \pi$?

<p>$\frac{x}{2}$ (D)</p> Signup and view all the answers

What does $3 \sin x = \sin^{-1} (3x - 4x^3)$ imply about the domain of $x$?

<p>$x \in [-\frac{1}{2}, \frac{1}{2}]$ (C)</p> Signup and view all the answers

What is the result of $\tan^{-1}(\frac{2\sin^{-1} x}{1 + x^2})$ for $|x| < 1$?

<p>$\sin^{-1}(x)$ (C)</p> Signup and view all the answers

What is the total number of elements in matrix A?

<p>12 (C)</p> Signup and view all the answers

Which of the following pairs of indices corresponds to the element -5 in matrix A?

<p>(3, 3) (C)</p> Signup and view all the answers

If a matrix has 24 elements, which of the following is NOT a possible order for this matrix?

<p>5 x 5 (C)</p> Signup and view all the answers

What is the value of a23 in matrix A?

<p>5 (D)</p> Signup and view all the answers

Which equation can be used to represent the element at position (i, j) in a 2 x 2 matrix where aij = (i + j)² / 2?

<p>a12 = 1.5 (D)</p> Signup and view all the answers

Which properties does the relation R = {(1, 2), (2, 1)} exhibit?

<p>Symmetric but neither reflexive nor transitive (D)</p> Signup and view all the answers

In which of the following relations is R = {(x, y): x and y have the same number of pages} not an equivalence relation?

<p>Relation based on the genre of the books (C)</p> Signup and view all the answers

Which set exhibits an equivalence relation with the property R = {(a, b): |a - b| is even}?

<p>{1, 3, 5} and {2, 4} (C)</p> Signup and view all the answers

Which relation is NOT an equivalence relation?

<p>R = {(a, b): a &gt; b} (B)</p> Signup and view all the answers

In the relation R = {(P, Q): distance of point P from the origin is same as point Q from the origin}, what shape is formed by all related points?

<p>Circle (B)</p> Signup and view all the answers

Which of the following triangles are similar among T₁ (3, 4, 5), T₂ (5, 12, 13), and T₃ (6, 8, 10)?

<p>T₁ and T₃ (B)</p> Signup and view all the answers

What type of relation is represented by R = {(L₁, L₂): L₁ is parallel to L₂}?

<p>Equivalence relation (D)</p> Signup and view all the answers

Which example is reflexive and symmetric but not transitive?

<p>R = {(a, b): a loves b and b loves a} (C)</p> Signup and view all the answers

Which relation is an example of being transitive but neither reflexive nor symmetric?

<p>R = {(x, y): x &lt; y} (D)</p> Signup and view all the answers

What is the value of $ an^{-1}ig( anig( rac{3 heta}{4}ig)ig)$?

<p>$ rac{3 heta}{4}$ (A)</p> Signup and view all the answers

Which expression represents $ an^{-1}ig( anig( rac{3 heta}{4}ig)ig)$ correctly?

<p>$ rac{3 heta}{4}$, for $ heta$ in $(- rac{ heta}{2}, rac{ heta}{2})$ (B)</p> Signup and view all the answers

What is the principal value of $ an^{-1}ig( anig( rac{3 heta}{4}ig)ig)$ when $ rac{3 heta}{4}$ exceeds the principal range?

<p>$ rac{3 heta}{4} - heta$ (A)</p> Signup and view all the answers

The expression $ an^{-1}ig( anig( rac{3 heta}{4}ig)ig)$ relates to which trigonometric property?

<p>Oddness of tangent (A)</p> Signup and view all the answers

Evaluate the expression $ an^{-1}ig( anig( rac{3 heta}{4}ig)ig)$. If this angle is negatively expressed, what will be the adequate answer?

<p>$ rac{3 heta}{4} - heta$ (B)</p> Signup and view all the answers

Flashcards

One-to-one function

A function where each element in the domain maps to a unique element in the codomain.

Onto function

A function where every element in the codomain has at least one corresponding element in the domain.

Injective function (One-to-one)

A function where different inputs map to different outputs.

Surjective function (Onto)

A function where every element in the codomain has at least one pre-image in the domain

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Greatest Integer Function

A function that maps a real number to the greatest integer less than or equal to that number.

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Reflexive relation in a set

A relation R in a set A is reflexive if (a, a) ∈ R for every element a in A.

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Symmetric relation in a set

A relation R in a set A is symmetric if whenever (a, b) ∈ R, then (b, a) ∈ R.

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Transitive relation in a set

A relation R in a set A is transitive if whenever (a, b) ∈ R and (b, c) ∈ R, then (a, c) ∈ R.

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Relation R in Z defined as R = {(x, y): x-y is integer}

The relation of integers where the subtraction result of x from y is always an integer; therefore always reflexive, symmetric, and transitive

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Reflexive Relation

A relation R on a set A is reflexive if (a, a) ∈ R for every element a ∈ A.

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Symmetric Relation

A relation R on a set A is symmetric if (a, b) ∈ R implies (b, a) ∈ R for all a, b ∈ A.

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Transitive Relation

A relation R on a set A is transitive if (a, b) ∈ R and (b, c) ∈ R implies (a, c) ∈ R for all a, b, c ∈ A.

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Equivalence Relation

A relation that is reflexive, symmetric, and transitive.

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(a, b) ∈ R means 'a relates to b'

In a relation R between elements a and b, (a, b) ∈ R signifies that element a is related to element b under relation R.

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Relation in a Set

A set of ordered pairs from a set to itself.

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Example of Symmetric Relation

{(1,2), (2,1)}

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Example of Equivalence Relation

Books with same number of pages.

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Equivalence Relation (|a-b| is even)

Elements with even difference between them in a set is related

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Different Types of Relations

Reflexive, symmetric, transitive, equivalence is classifications of relations based on their properties.

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Equivalence Relation Circles

Points at equal distances from a fixed point (origin) in the plane form an equivalence relation.

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sin⁻¹(-1/2)

The angle in the interval [-π/2, π/2] whose sine is -1/2.

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cos⁻¹(√3/2)

The angle in the interval [0, π] whose cosine is √3/2.

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cosec⁻¹(2)

The angle in the interval [-π/2, π/2] whose cosecant is 2.

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tan⁻¹(-√3)

The angle in the interval (-π/2, π/2) whose tangent is -√3.

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cos⁻¹(-1/2)

The angle in the interval [0, π] whose cosine is -1/2.

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Modulus Function

The function that maps any real number to its absolute value. It is defined as f(x) = |x|, where |x| is x if x is positive or 0, and |x| is -x if x is negative.

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Signum Function

The function that returns the sign of a real number. It is defined as f(x) = 1 for x > 0, f(x) = 0 for x = 0, and f(x) = -1 for x < 0.

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Bijective Function

A function that is both one-to-one and onto. This means each element in the domain maps to a unique element in the codomain, and every element in the codomain has a corresponding element in the domain.

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Inverse trigonometric functions

Functions that return the angle (in radians) corresponding to a given trigonometric value (sine, cosine, tangent, etc.). For example, arcsin(x) returns the angle whose sine is x.

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What is sec⁻¹(2/√3)?

The angle whose secant is 2/√3. Since secant is the reciprocal of cosine, find the angle whose cosine is √3/2. This angle is π/6 radians.

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What is cot⁻¹(√3)?

The angle whose cotangent is √3. Since cotangent is the reciprocal of tangent, find the angle whose tangent is 1/√3. This angle is π/6 radians.

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What is the range of y in sin⁻¹(x) = y?

The range of y is 0 ≤ y ≤ π. This is because the sine function has a range of [-1, 1], and the inverse sine function only returns angles within the principal branch of the sine function, from -π/2 to π/2.

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Calculate tan⁻¹(√3) - sec⁻¹(-2)

tan⁻¹(√3) = π/3 and sec⁻¹(-2) = -π/3. So, the answer is π/3 - (-π/3) = 2π/3.

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Simplest form (inverse trigonometric)

Expressing an inverse trigonometric function in terms of its base trigonometric function. For example, expressing $\cot^{-1} \sqrt{x^2-1}$ as $\sec^{-1} x$.

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Prove a trigonometric identity involving inverse functions

Show that two trigonometric expressions involving inverse functions are equivalent for a specific range of values. This involves manipulation of trigonometric identities and properties of inverse functions.

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Write a function in simplest form (inverse trigonometric)

Simplify a given expression containing inverse trigonometric functions by using trigonometric identities, algebraic manipulation, and properties of inverse functions.

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Find the value of a composite trigonometric function

Calculate the value of an expression involving multiple inverse and regular trigonometric functions, often including nested functions. This involves applying the properties and definitions of inverse functions sequentially.

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Matrix Order

The dimensions of a matrix, represented as rows x columns.

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Elements in a Matrix

The individual values within a matrix. They can be numbers, variables, or expressions.

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Matrix Element Notation

Using 'aij' to represent the element in the i-th row and j-th column.

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Constructing a Matrix

Creating a matrix using a formula that defines the relationship between row and column indices to determine each element's value.

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Matrix Equation (solving)

A system of equations represented using matrices, where the unknown variables are arranged into a matrix.

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Inverse Sine Function

The inverse sine function, denoted as sin⁻¹(x) or arcsin(x), finds the angle whose sine is x. It's the inverse operation of the sine function, giving an angle within the range of -π/2 to π/2.

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Inverse Tangent Function

The inverse tangent function, written as tan⁻¹(x) or arctan(x), finds the angle whose tangent is x. It's the inverse of the tangent function, resulting in an angle within the range of -π/2 to π/2.

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Inverse Cosine Function

The inverse cosine function, represented as cos⁻¹(x) or arccos(x), finds the angle whose cosine is x. It's the inverse of the cosine function, yielding an angle in the range of 0 to π.

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Principal Branch

Within the inverse trigonometric functions, the principal branch refers to the specific range of output angles that the function provides. For example, the principal branch of arcsine is from -π/2 to π/2.

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Simplify Trig Expressions with Inverse Functions

To simplify expressions involving inverse trigonometric functions, use the inverse operation to get the original angle, check if the angle lies within the principal branch, and find an equivalent angle that's within the principal branch if necessary. This ensures the simplified expression is consistent with the function's definition.

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How to determine if a relation is reflexive, symmetric, or transitive?

To check whether a relation R on a set A is reflexive, symmetric, or transitive, you need to examine the ordered pairs in R and see if they satisfy the conditions for each property.

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