Chapter 3: Problem 10
The area bounded by \(y=2-|2-x|\) and \(y=\frac{3}{|x|}\) is (a) \(\frac{4+3 \ln 3}{2}\) (b) \(\frac{19}{8}-3 \ln 2\) (c) \(\frac{3}{2}+\ln 3\) (d) \(\frac{1}{2}+\ln 3\)
Short Answer
Expert verified
(d) \( \frac{1}{2} + \ln 3 \) is the area bounded by the graphs.
Step by step solution
01
Understand the Graphs
The function \( y = 2 - |2 - x| \) is a V-shaped graph centered at \( x = 2 \), and \( y = \frac{3}{|x|} \) is a hyperbola with vertical asymptotes at \( x = 0 \). Our goal is to find where these graphs intersect, determine the portion of the area bounded by them, and compute that area.
02
Find Intersection Points
To find where \( y = 2 - |2 - x| \) intersects with \( y = \frac{3}{|x|} \), consider the piecewise forms. For \( x \leq 2 \), \( 2 - |2 - x| = x \). Set \( x = \frac{3}{|x|} \), leading to solving \( x^2 = 3 \) or \( x = \pm \sqrt{3} \). Both \( \pm \sqrt{3} \) are valid as long as they fall on the correct piece of the piecewise function. Similarly, for \( x > 2 \), \( y = 2 - |2 - x| = 4 - x \). Solve \( 4 - x = \frac{3}{x} \) to find \( x = 3 \) by checking if this value satisfies the inequality for this piece of the function.
03
Calculate Areas Under Curves
Calculate the area bounded between \( x = -\sqrt{3} \) and \( x = \sqrt{3} \) by evaluating the integral \( \int_{-\sqrt{3}}^{\sqrt{3}} (x - \frac{3}{|x|}) \, dx \), knowing that for \( x < 0 \), \( \frac{3}{|x|} = -\frac{3}{x} \). Similarly, calculate the area for \( x = \sqrt{3} \) to \( x = 3 \) by evaluating the integral \( \int_{\sqrt{3}}^{3} ((4 - x) - \frac{3}{x}) \, dx \).
04
Evaluate Integrals
Each integral from Step 3 needs to be calculated. For \( x < 0 \), \( \int_{-\sqrt{3}}^{0} (x + \frac{3}{x}) \, dx \), simplifies to evaluating \( \frac{x^2}{2} - 3 \ln |x| \) from \( -\sqrt{3} \) to \( 0 \). For \( x > 0 \), use \( \int_{0}^{3} ((4 - x) - \frac{3}{x}) \, dx \) and break each function into separate integrals: \( \int(4-x) \, dx \) and \( \int \frac{3}{x} \, dx \).
05
Compute Final Area
Combine the results of the integrals from Step 4. The evaluation will involve substituting suitable values and including the expression \( \ln |x| \) where needed. Sum the values of each segment to obtain the bounded area described in the options.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
V-shaped graph
A V-shaped graph is often associated with absolute value functions. For example, the function \( y = 2 - |2 - x| \) forms a V-shape. This particular graph is symmetric around the vertical line \( x = 2 \), which is where the vertex or the peak of the V-shape occurs.
To understand such a graph, consider its construction from piecewise linear functions. The absolute value causes it to combine two linear segments: one with a positive slope and another with a negative slope. Here’s how it breaks down:
To understand such a graph, consider its construction from piecewise linear functions. The absolute value causes it to combine two linear segments: one with a positive slope and another with a negative slope. Here’s how it breaks down:
- For \( x \leq 2 \), \( y = 2 - (2 - x) = x \). This part of the graph slopes upwards to the right.
- For \( x > 2 \), \( y = 2 - (x - 2) = 4 - x \). This part of the graph slopes downwards to the left, forming the symmetrical V shape.
hyperbola intersection
Hyperbolas have distinct properties compared to other conics, such as circles or parabolas. The function \( y = \frac{3}{|x|} \) represents the reciprocal function, forming a graph with two separate branches known as a hyperbola. This hyperbola tends towards infinity as \( x \) approaches zero but never actually touches the \( y \)-axis due to its vertical asymptote at \( x = 0 \).
When we talk about intersection points between the hyperbola \( y = \frac{3}{|x|} \) and another curve, such as the V-shaped graph mentioned earlier, solving these equations can reveal where the two graphs share common coordinates. Solving:
When we talk about intersection points between the hyperbola \( y = \frac{3}{|x|} \) and another curve, such as the V-shaped graph mentioned earlier, solving these equations can reveal where the two graphs share common coordinates. Solving:
- The V-shaped curve piece \( x \) for \( x \leq 2 \) equates to \( x = \frac{3}{|x|} \), leading to solutions like \( x = \pm \sqrt{3} \).
- For the post-vertex part \( 4-x \), setting \( 4-x = \frac{3}{x} \) results in a separate intersection at \( x = 3 \).
integral evaluation
Evaluating definite integrals helps in finding the area bounded by curves. To measure the area between the V-shaped graph \( y = 2 - |2 - x| \) and the hyperbola \( y = \frac{3}{|x|} \), each section of interest requires integration over distinct ranges.
For instance, to find the area where the hyperbola intersects, calculate:
For instance, to find the area where the hyperbola intersects, calculate:
- For \( x \leq 0 \): The integral \( \int_{-\sqrt{3}}^{0} (x + \frac{3}{x}) \, dx \) where simplifying the integral often results in expressions like \( \frac{x^2}{2} - 3 \ln |x| \).
- From \( x = \sqrt{3} \) to \( x = 3 \): Integrate \( (4-x) - \frac{3}{x} \), splitting it into simpler integrals such as \( \int (4-x) \, dx \) and \( \int \frac{3}{x} \, dx \).