Chapter 17: Problem 4
In Problems 1-6, find the image of the given line under the mapping \(f(z)=z^{2}\). $$ y=0 $$
Short Answer
Expert verified
The image of the line \(y=0\) under \(f(z)=z^2\) is the non-negative real axis \([0, \infty)\).
Step by step solution
01
Understand the Problem
We are given a line defined by the equation \(y=0\), which is the x-axis in the complex plane. We need to find the image of this line under the mapping \(f(z)=z^2\).
02
Express Points on the Line
We express any point on the line \(y=0\) as a complex number where the imaginary part is zero. Therefore, a point on the line is \(z = x + 0i = x\), where \(x\) is a real number.
03
Apply the Mapping
Apply the mapping \(f(z) = z^2\) to the points on the line. This means we replace \(z\) with \(x\) in the expression for \(f(z)\).
04
Calculate the Image
Since \(z = x\), the map becomes \(f(x) = x^2\). By squaring any real number \(x\), the imaginary part remains zero, as \((x)^2 = x^2 + 0i\). Thus, the image is the real line, where each \(x\) on \(y = 0\) maps to \(x^2\) on \(y=0\).
05
Determine the Range of the Image
The range of values for \(x^2\) is from \(0\) to \(\infty)\) for all real numbers \(x\). Therefore, the image is the non-negative real axis, \([0, \infty)\), on the real line.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Complex Mapping
In the world of complex analysis, a complex mapping can be thought of as a transformation of the complex plane. Mapping functions take each point from one complex space and transform it into another space. A common type of mapping is when a function takes a complex number and produces another complex number. In our exercise, for example, we use the mapping function \(f(z) = z^2\).
- Each input \(z\) is a point on the complex plane represented by \(x+yi\), where \(x\) and \(y\) are real numbers, and \(yi\) is the imaginary part.
- The operation \(z^2\) transforms this point by "squaring" the complex number.
- For the specific problem, since \(y=0\), we simplify \(z\) into just \(x\).
Complex Plane
The complex plane is a two-dimensional space where every point corresponds to a complex number. This plane is pivotal in complex analysis, bridging the gap between the imaginaries and reals.
- The horizontal axis, also known as the real axis, represents all real numbers.
- The vertical axis, called the imaginary axis, represents all imaginary numbers \(yi\).
Imaginary Part
The imaginary part of a complex number is what makes complex numbers unique. It is denoted by \(i\) and is a critical component of the complex plane.
- A complex number is structured as \(z = x + yi\), where \(x\) is the real part, and \(yi\) is the imaginary part.
- The imaginary part is zero on the real axis, which is the line we are dealing with in our exercise.
Real Axis
The real axis on the complex plane is a concept that many are already familiar with—it works just like the number line from real number systems, but it is a vital component of the complex plane. In this plane:
- The real axis is where all imaginary parts of complex numbers are zero.
- It stretches horizontally, meaning all points on it have only real values.