Chapter 8: Problem 9
Sketch the graph of the inequality. $$y x^{2} \geq 1$$
Short Answer
Expert verified
Shade the region above the curve of \( y = \frac{1}{x^2} \).
Step by step solution
01
Rewrite the Inequality
First, rewrite the inequality to make it easier for analysis. The given inequality is \( y x^2 \geq 1 \). We can write it in terms of \( y \): \[ y \geq \frac{1}{x^2} \] This gives us a function \( y = \frac{1}{x^2} \), which represents the boundary of the inequality.
02
Analyze the Boundary Function
Now, analyze the function \( y = \frac{1}{x^2} \). This is a rational function that has the following characteristics: 1. The function is undefined at \( x = 0 \) due to division by zero.2. For \( x > 0 \) and \( x < 0 \), the function is defined and positive.3. The function approaches infinity as \( x \) approaches zero from either direction (left or right). 4. The function approaches zero as \( x \) moves away from the origin towards positive or negative infinity.
03
Plot the Boundary Function
Next, sketch the graph of the boundary function \( y = \frac{1}{x^2} \). It will be a curve in the first and second quadrants where:- As \( x \to 0^+ \) or \( x \to 0^- \), \( y \to \infty \).- As \( x \to \infty \) or \( x \to -\infty \), \( y \to 0 \).
04
Shade the Appropriate Region
Since the inequality is \( y \geq \frac{1}{x^2} \), shade the region above the curve \( y = \frac{1}{x^2} \). This includes all points where the value of \( y \) is equal to or greater than \( \frac{1}{x^2} \). This region will include lines going outward from both branches of the hyperbola.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Rational Functions
A rational function is a type of function that is represented by the ratio of two polynomials. It is expressed in the form \( f(x) = \frac{P(x)}{Q(x)} \), where both \( P(x) \) and \( Q(x) \) are polynomials, and \( Q(x) eq 0 \). In the context of the exercise, the rational function is given by \( y = \frac{1}{x^2} \). Here, \( P(x) = 1 \) and \( Q(x) = x^2 \). Some important properties of rational functions include:
- They can have vertical asymptotes where the denominator is zero, as seen when \( x = 0 \) since \( \frac{1}{x^2} \) is undefined at this point.
- They can have horizontal or slant asymptotes, which help in describing the end behavior of the function.
- They often result in curves or graphs with distinct characteristics, such as hyperbolas.
Quadrants
In the Cartesian plane, a quadrant is one of the four sections created by dividing the plane with an x-axis and a y-axis. These axes intersect at the origin \( (0, 0) \). Starting from the upper right and moving counter-clockwise, the quadrants are numbered:
- First Quadrant (I): Where x and y are both positive.
- Second Quadrant (II): Where x is negative and y is positive.
- Third Quadrant (III): Where both x and y are negative.
- Fourth Quadrant (IV): Where x is positive and y is negative.
Shading Regions
When graphing inequalities such as \( y \geq \frac{1}{x^2} \), a crucial step is shading the appropriate region of the graph. This process indicates the set of points that satisfy the inequality conditions. In this inequality:- We graph the boundary curve first, \( y = \frac{1}{x^2} \).- Then we determine which side of this curve satisfies \( y \geq \frac{1}{x^2} \), which is the region above the graph.To ensure you have shaded the correct region:
- Choose a test point located in each possible shading region (e.g., \( (1, 2) \)).
- Substitute the coordinates of these points into the inequality.
- If the inequality holds true for a test point, shade the region containing this point.
Hyperbola
A hyperbola is a type of smooth curve lying on a plane, defined by its distinct geometry. It's usually the result of slicing a double conic section in a unique way. In terms of functions and graphs, a rational function like \( y = \frac{1}{x^2} \) exhibits hyperbolic characteristics, as parts of its graph resemble hyperbolas. Characteristics of hyperbolas include:
- They consist of two disconnected, mirror-image branches, as seen in this exercise.
- Each branch approaches, but never intersects, specific asymptotes, which are lines the curve gets arbitrarily close to.
- The center at \( x = 0 \) represents a point of infinite discomfort, a point the branches veer away from.