Functions: Definitions and Types
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Questions and Answers

Which of the following statements accurately describes a rational function, as defined in the text provided?

  • A function that can be expressed as the ratio of two polynomial functions, where the denominator cannot be zero. (correct)
  • A function whose graph has no asymptotes.
  • A function that can be expressed as a sum of terms, each of which involves a constant multiplied by a power of the input variable.
  • A function whose domain is always all real numbers.
  • Consider the function f(x) = log₂(x + 3). Which of the following values is NOT in the domain of this function?

  • -2
  • -3 (correct)
  • 1
  • 5
  • A function f(x) is called 'onto' if:

  • Every element in the domain is mapped to by at least one element in the range.
  • Every element in the range is mapped to by exactly one element in the domain.
  • No two elements in the domain are mapped to the same element in the range.
  • Every element in the range is mapped to by at least one element in the domain. (correct)
  • What is the degree of the polynomial function y = 3x⁵ - 2x² + x + 7?

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

    Which of the following functions is NOT bijective?

    <p>f(x) = x² (x ≥ 0) (C)</p> Signup and view all the answers

    Which of the following is a characteristic of a linear function?

    <p>It has a constant rate of change. (B)</p> Signup and view all the answers

    Given the function f(x) = 2x - 3, what is the value of f(5)?

    <p>7 (C)</p> Signup and view all the answers

    What is the relationship between exponential functions and logarithmic functions?

    <p>They are inverse functions of each other. (C)</p> Signup and view all the answers

    What is the primary purpose of a graph in the context of functions?

    <p>To visually represent the relationship between input and output (A)</p> Signup and view all the answers

    Which of the following scenarios would restrict the domain of a function?

    <p>The function involves a square root of a negative number (D)</p> Signup and view all the answers

    When performing operations on functions, what is not a possible result?

    <p>Dividing one function by another and finding a constant result (B)</p> Signup and view all the answers

    How can one determine the inverse of a function?

    <p>By swapping the x and y values in the function's equation and solving for y (A)</p> Signup and view all the answers

    What is the definition of function composition?

    <p>Using the output of one function as the input to another function (D)</p> Signup and view all the answers

    Study Notes

    Functions: Definitions and Basic Concepts

    • A function is a relation between a set of inputs (domain) and a set of possible outputs (range) with the property that each input is related to exactly one output.
    • Functions are often represented by equations, where the output (often denoted by 'y' or 'f(x)') depends on the input (often denoted by 'x').
    • The domain of a function is the set of all possible input values. This might be all real numbers, or a subset thereof.
    • The range of a function is the set of all possible output values.

    Types of Functions

    • Linear functions: These functions have the general form y = mx + b, where 'm' is the slope and 'b' is the y-intercept. The graph of a linear function is a straight line.
    • Quadratic functions: These functions have the general form y = ax² + bx + c, where 'a', 'b', and 'c' are constants. The graph of a quadratic function is a parabola.
    • Polynomial functions: These functions involve exponents of the input variable (x), like y = x³ − 2x² + 4x + 1. The highest power of x determines the degree of the polynomial.
    • Rational functions: These involve quotients of polynomial functions, like y = (x² + 2x) / (x - 1). Defined for all values of x except those that make the denominator zero.
    • Exponential functions: These functions have the general form y = ax, where 'a' is a constant, describes growth or decay. Exponents are the input value.
    • Logarithmic functions: These are the inverse of exponential functions, i.e. they solve the problem of finding the exponent. General form: y = loga(x).

    Function Notation

    • Using 'f(x)' notation, 'f' represents the function name; 'x' represents an input to the function; 'f(x)' represents the output for the corresponding input

    Function Properties

    • One-to-one functions: Each output corresponds to exactly one input. A horizontal line drawn through the graph will cross it at most one time.
    • Onto functions: A function is onto or surjective if every element in the range is mapped to by at least one element in the domain.
    • Injective functions: As above, each output corresponds to exactly one input.
    • Bijective functions: A bijective function is one that is both one-to-one and onto: each element in the range is related to exactly one element in the domain, and each element in the domain is related to exactly one element in the range. Often they have inverse functions.

    Graphing Functions

    • Graphs provide a visual representation of the relationship between the input and output.
    • The x-axis typically represents the input (domain) and the y-axis represents the output (range).
    • Key features like intercepts (where the graph crosses the axes), maxima/minima, and asymptotes can be identified from the graph.

    Domain and Range

    • Determining the domain and range often involves considering the definition of the function and potential restrictions on the input values to avoid division by zero, non-real number outputs or undefined values.

    Function Operations

    • Functions can be added, subtracted, multiplied, or divided, creating new functions.

    Inverse Functions

    • An inverse function reverses the effect of a given function.
    • Finding an inverse function might involve switching x and y in the function's equation and then solving for y.

    Composition of Functions

    • Combining functions such that the output of one function is the input of another function is often called composition of functions.
    • The notation for composition of function f and g could be written f(g(x)).

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    Description

    This quiz explores the fundamental concepts of functions, including their definitions, domains, and ranges. You'll also learn about different types of functions such as linear, quadratic, and polynomial functions, alongside their equations and graphical representations.

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