MATH100 Precalculus Lecture Notes
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Questions and Answers

What is the outcome when substituting $x = 0$ into the inequality $2x^2 - 3x + 1 ≤ 0$?

  • True, the inequality holds.
  • True, it equals zero.
  • False, it results in a negative value.
  • False, it yields a result greater than zero. (correct)
  • Which test point correctly supports the interval $(-1/2, 1)$ solving the inequality?

  • $x = 1$ results in a true statement.
  • $x = 0$ yields a false result.
  • $x = 1/2$ gives a true statement. (correct)
  • $x = -1/2$ produces a false outcome.
  • What does the tested point $x = 2$ reveal about the interval $(1, ext{∞})$?

  • It supports the interval by yielding a negative value.
  • It refutes the interval as it gives a positive value. (correct)
  • It confirms the interval by yielding true.
  • It provides no relevant information about the interval.
  • What is the correct solution set for the inequality $2x^2 - 3x + 1 ≤ 0$ based on tested intervals?

    <p>(-1/2, 1] as a closed interval.</p> Signup and view all the answers

    In solving $2x^2 - 3x + 1 ≤ 0$, which conclusion can be drawn from testing $x = -1/2$?

    <p>It yields a negative value supporting the interval.</p> Signup and view all the answers

    What defines the domain of a function?

    <p>The set of all possible values of $x$</p> Signup and view all the answers

    Which of the following statements is true regarding a function?

    <p>A function must have a one-to-one relationship between $x$ and $y$</p> Signup and view all the answers

    What happens in computing when a division by zero occurs?

    <p>It can lead to system failures due to buffer overruns</p> Signup and view all the answers

    In the context of functions, what does the range represent?

    <p>The set of all output values ($y$) when $x$ is in the domain</p> Signup and view all the answers

    Why is dividing by zero prohibited in mathematics?

    <p>It results in infinity, which cannot be handled</p> Signup and view all the answers

    What is the domain of the function $g(x) = -3x^2 + 4x + 5$?

    <p>All real numbers</p> Signup and view all the answers

    For the function $f(x) = \frac{x-4}{x+3}$, what value must be excluded from the domain?

    <p>-3</p> Signup and view all the answers

    What is the domain of the function $f(x) = \frac{x+1}{(x-3)(x+5)}$?

    <p>All real numbers except 3 and -5</p> Signup and view all the answers

    What is the domain of the function $f(x) = \frac{4}{x^2 - 9}$?

    <p>All real numbers except 3 and -3</p> Signup and view all the answers

    For the function $f(x) = \frac{x-1}{x^2 + 4x + 3}$, which values are excluded from the domain?

    <p>-1 and -3</p> Signup and view all the answers

    What is the domain of the function $f(x) = \frac{5}{x^2 + 9}$?

    <p>All real numbers</p> Signup and view all the answers

    What values need to be excluded from the domain for the function $f(x) = \frac{x}{x-1}$?

    <p>1 only</p> Signup and view all the answers

    From the graph of the function $f(x) = x + 3$, what is the domain?

    <p>[–3, ∞)</p> Signup and view all the answers

    What is the domain of the function $f(x) = \frac{1}{x}$?

    <p>All real numbers except 0</p> Signup and view all the answers

    In the function $f(x) = x^2 + 1$, which of the following is true about its domain?

    <p>It includes all real numbers</p> Signup and view all the answers

    What is the solution set for the inequality $3x - 2 + 3 \geq 11$?

    <p>$x \in (-\infty, -2) \cup (\frac{10}{3}, \infty)$</p> Signup and view all the answers

    Which of the following describes the equivalent form of the inequality $2x + 1 > 9$?

    <p>$2x + 1 &lt; -9 ; OR ; 2x + 1 &gt; 9$</p> Signup and view all the answers

    What does the Vertical Line Test assess regarding a graph?

    <p>If the graph is a function</p> Signup and view all the answers

    For the case when $x < a$, where $a > 0$, what is the equivalent inequality?

    <p>$-a &lt; x &lt; a$</p> Signup and view all the answers

    What defines the set of rational numbers?

    <p>All numbers that can be expressed as a fraction of two integers.</p> Signup and view all the answers

    What is a condition for a relation to be considered a function?

    <p>Each input must correspond to exactly one output</p> Signup and view all the answers

    Identify the solution set for the inequality $2x - 4 > 8$.

    <p>$x ∈ (6, ∞)$</p> Signup and view all the answers

    Which statement is true regarding the inequality $x - 3 < 5$?

    <p>$-5 &lt; x - 3 &lt; 5$</p> Signup and view all the answers

    What is the solution for the inequality $2x + 1 < -9$?

    <p>$x &lt; -5$</p> Signup and view all the answers

    What is the solution set for the inequality $2x + 1 < -9$?

    <p>$x &lt; -5$</p> Signup and view all the answers

    What technique is used to solve the inequality $2x^2 - 3x + 1 ≤ 0$?

    <p>Factoring the quadratic equation.</p> Signup and view all the answers

    In the context of absolute value inequalities, what does $x > a$ result in?

    <p>$x &lt; -a$ or $x &gt; a$</p> Signup and view all the answers

    When testing the intervals from the equation $2x^2 - 3x + 1 = 0$, what must be done first?

    <p>Find the zeros and create intervals around them.</p> Signup and view all the answers

    Which of the following sets contains only integers?

    <p>$Z = {..., -2, -1, 0, 1, 2, ...}$</p> Signup and view all the answers

    Which statement is true about irrational numbers?

    <p>They include numbers like π and e.</p> Signup and view all the answers

    What does the notation $x ∈ (−∞, −5)$ indicate?

    <p>x is less than -5 and does not include -5.</p> Signup and view all the answers

    Study Notes

    MATH100 Precalculus - Lecture Notes

    • Lecture #1: Covers introduction to functions, solving inequalities, and domain and range of a function.

    Real Numbers

    • Real numbers are the combination of rational and irrational numbers.
    • Rational numbers (Q): Numbers that can be expressed as a fraction p/q, where p and q are integers and q ≠ 0. Examples: -1/2, 0, 3, 2.5.
    • Irrational numbers (Q'): Numbers that cannot be expressed as a fraction of two integers. Examples: π, √2, √3
    • Integers (Z): Whole numbers, including zero and negative numbers. Examples: ..., -3, -2, -1, 0, 1, 2, 3,...
    • Natural numbers (N): Positive whole numbers. Examples: 1, 2, 3,...

    Solving Inequalities: Examples

    • Example 1: Solving 2x - 4 > 8 results in x > 6. The solution set is x ∈ (6, ∞).
    • Example 2: Solving 2x + 1 < -9 results in x < -5. The solution set is x ∈ (-∞, -5).
    • Example 3: Solving 1 - 2x < 9 (needs the solution)
    • Example 4: Solving 2x² - 3x + 1 ≤ 0 results in the interval [1/2, 1].
      • Finding zeros of 2x² - 3x + 1 = 0: x = 1/2 and x = 1.
      • Testing intervals to determine the solution set to the inequality.

    Absolute Value Inequalities: Examples

    • Case 1: |x| < a is equivalent to −a < x < a
    • Case 2: |x| > a is equivalent to x < −a or x > a
    • Example 1: Solving |x − 3| < 5 results in −2 < x < 8. The solution set is x ∈ (−2, 8).
    • Example 2: Solving |2x + 1| > 9 results in x < −5 or x > 4. The solution set is x ∈ (−∞, −5) ∪ (4, ∞).
    • Example 3: Solving |3x − 2| + 3 ≥ 11 results in x ≥ 10/3 or x ≤ −2/3. The solution set is x ∈ (−∞, −2/3] ∪ [10/3, ∞).

    Function Definition

    • A function is a relation that assigns each input value to exactly one output value.
    • The notation is y = f(x), where x is the input, y is the output, and f is the function.
    • Examples include y = x², y = √x.
    • Function examples are plotted (parabolas, sine waves, circles)

    The Vertical Line Test

    • A graph represents a function if no vertical line intersects the graph at more than one point.

    Domain and Range of a Function

    • Domain: The set of all possible input values (x-values) for which the function is defined.

    • Range: The set of all possible output values (y-values) that the function can produce.

    • Examples:

      • Example 1: g(x) = −3x² + 4x + 5 has a domain of all real numbers.
      • Example 2: f(x) = (x-4)/(x+3) has a domain of all real numbers except x = -3.
      • Example 3: f(x) = (x+1)/((x-3)(x+5)) has a domain of all real numbers except x = 3 and x = -5.
      • Example 4: f(x) = 4/(x²−9) has a domain of all real numbers except x = 3 and x = −3
      • Example 5: f(x) = (x-1)/(x² + 4x + 3) has a domain of all real numbers except x = −1 and x=−3
    • Finding domain and range from graphs: visual analysis

    • Why aren't we allowed to divide by zero? A historical example of a real-world problem stemming from attempting to divide by zero in computer code.

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    Description

    This quiz covers key concepts from MATH100 Precalculus, including an introduction to functions, real numbers, and methods for solving inequalities. Participants will explore types of numbers such as rational, irrational, integers, and natural numbers, along with practical examples of solving inequalities. Prepare to test your knowledge on these foundational topics!

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