Chapter 1: Problem 17
Find the limits using your understanding of the end behavior of each function. $$\lim _{x \rightarrow-\infty} x^{2}$$
Short Answer
Expert verified
The limit is \( \infty \).
Step by step solution
01
Understand the Function
The function in question is a simple polynomial: \( f(x) = x^2 \), where the degree of the polynomial is 2 (a quadratic function). The highest exponent on \( x \) is 2, which determines the behavior of the function as \( x \) approaches either \( \infty \) or \( -\infty \).
02
Analyze End Behavior As \( x \rightarrow -\infty \)
For polynomial functions like \( f(x) = x^2 \), the sign of the leading coefficient (which is positive in this case) influences the end behavior. Since the function is \( x^2 \), for any real number \( x \), whether negative or positive, the result is always a non-negative value due to the squaring. Specifically, as \( x \) approaches \( -\infty \), \( x^2 \) grows larger and larger to positive infinity.
03
Determine the Limit
Based on the analysis, as \( x \) tends to \( -\infty \), the term \( x^2 \) continues to increase without bound in the positive direction. Therefore, we conclude that \( \lim_{x \to -\infty} x^2 = \infty \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
End Behavior
End behavior in functions refers to the behavior of a graph or equation as the input variable moves towards extreme values, either positive infinity or negative infinity. For polynomial functions like quadratic equations (e.g., \( x^2 \)), end behavior helps us predict how the function behaves as \( x \) becomes very large or very small.
To analyze end behavior, focus on the leading term with the highest exponent. This term dominates all others when \( x \) is extremely large or small. Here, in the function \( f(x) = x^2 \), since the highest order term is \( x^2 \), it determines the end behavior.
Generally:
To analyze end behavior, focus on the leading term with the highest exponent. This term dominates all others when \( x \) is extremely large or small. Here, in the function \( f(x) = x^2 \), since the highest order term is \( x^2 \), it determines the end behavior.
Generally:
- If the leading coefficient is positive, the function will move towards positive infinity as \( x \) approaches either \( +∞ \) or \( -∞ \).
- If the leading coefficient is negative, the function will tilt towards negative infinity.
Polynomial Function
A polynomial function is a mathematical expression consisting of variables and coefficients combined using addition, subtraction, multiplication, and non-negative integer exponents. Examples include \( x^2 + 2x + 1 \), \( 3x^3 - x + 4 \), or simply \( x^2 \) as in our exercise.
Key characteristics of polynomial functions:
Key characteristics of polynomial functions:
- The degree of the polynomial is determined by the highest exponent on the variable.
- The leading coefficient, associated with the highest power term, heavily influences the behavior of the polynomial for large values of \( x \).
- Polynomials are continuous and smooth, with no breaks or sharp edges in their graphs.
Quadratic Function
A quadratic function is a specific type of polynomial where the highest power of the variable is 2. The standard form of a quadratic function can be written as \( ax^2 + bx + c \), where \( a \), \( b \), and \( c \) are constants, and \( a eq 0 \).
For example, our function, \( f(x) = x^2 \), is a simple quadratic with \( a = 1 \), \( b = 0 \), and \( c = 0 \). Quadratics typically create a parabolic shape when graphed, opening upwards if the leading coefficient \( a \) is positive, and downwards if \( a \) is negative.
Not only do quadratic functions help in understanding maximum and minimum values, but they are also critical in analyzing end behavior.
Characteristics of quadratic functions include:
For example, our function, \( f(x) = x^2 \), is a simple quadratic with \( a = 1 \), \( b = 0 \), and \( c = 0 \). Quadratics typically create a parabolic shape when graphed, opening upwards if the leading coefficient \( a \) is positive, and downwards if \( a \) is negative.
Not only do quadratic functions help in understanding maximum and minimum values, but they are also critical in analyzing end behavior.
Characteristics of quadratic functions include:
- The vertex, which can be a minimum or maximum point, determines the turning point of the graph.
- The axis of symmetry, which is a vertical line through the vertex, splits the parabola into two mirror-image halves.
- Quadratics have a single curve with no breaks, hence the smooth 'U' shape or an inverted 'U' if the parabola opens downward.