Chapter 2: Problem 1
Plot the images of the complex numbers \(z=1,1+i, 1-i\), and \(i\) under the given function \(f\) as position vectors, and (b) plot the images as vectors in the vector field associated with \(f\).\(f(z)=2 z-i\)
Short Answer
Expert verified
The images of the numbers are: 2-i, 2+i, 2-3i, and i as position vectors and vectors in the vector field.
Step by step solution
01
Understanding the Function
The function given is \(f(z) = 2z - i\). This means for any complex number \(z\), we first multiply it by 2 and then subtract \(i\) from the result. Our goal is to find the transformed images of the complex numbers \(z = 1, 1+i, 1-i,\) and \(i\).
02
Calculating f(z) for z=1
Substitute \(z = 1\) into the function: \(f(1) = 2(1) - i = 2 - i\). The image of \(z = 1\) under the function is the complex number \(2 - i\).
03
Calculating f(z) for z=1+i
Substitute \(z = 1+i\) into the function: \(f(1+i) = 2(1+i) - i = 2 + 2i - i = 2 + i\). The image of \(z = 1+i\) is the complex number \(2 + i\).
04
Calculating f(z) for z=1-i
Substitute \(z = 1-i\) into the function: \(f(1-i) = 2(1-i) - i = 2 - 2i - i = 2 - 3i\). The image of \(z = 1-i\) is the complex number \(2 - 3i\).
05
Calculating f(z) for z=i
Substitute \(z = i\) into the function: \(f(i) = 2i - i = i\). The image of \(z = i\) is the complex number \(i\).
06
Plotting Position Vectors
On the complex plane, plot the points corresponding to the images: \(2-i\), \(2+i\), \(2-3i\), and \(i\). These points should be plotted as position vectors from the origin (0,0).
07
Plotting Vectors in Vector Field
For each complex number transformation result, draw a vector on the complex plane starting at the origin pointing towards each image: \(2-i\), \(2+i\), \(2-3i\), and \(i\). This demonstrates the vector field behavior of the function \(f(z)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Complex Numbers
Complex numbers are an extension of the real numbers and include a real part and an imaginary part. They are usually expressed in the form of \( z = a + bi \), where \( a \) is the real part, and \( b \) is the imaginary part accompanied by the imaginary unit \( i \). The imaginary unit \( i \) is defined by the property \( i^2 = -1 \). This allows us to handle square roots of negative numbers effectively.
- Real Part: The component \( a \) in the expression \( z = a + bi \).
- Imaginary Part: The component \( bi \) in the expression.
Vector Field
A vector field is a representation that assigns a vector to every point in a given space. In the case of complex functions, this space is often the complex plane. Each point on the plane is associated with a complex number, and the complex function assigns a new complex number, effectively a vector, to each point.
- The arrow of the vector indicates the direction of the transformation.
- The length of the arrow can represent the magnitude of the transformation.
Complex Plane
The complex plane is a two-dimensional plane used to represent complex numbers geometrically. It consists of a horizontal axis, called the real axis, and a vertical axis, called the imaginary axis.
- Real Axis: The axis along which the real part of a complex number is measured.
- Imaginary Axis: The axis along which the imaginary part of a complex number is measured.
Transformation
Transformation refers to the process of applying a function to a set of complex numbers to obtain a new set of numbers in the complex plane. This is what happens in our exercise when we use the function \( f(z) = 2z - i \) on the given points.
- Mapping: Each complex number \( z \) is mapped to a new number \( f(z) \).
- Steps: The transformation involves multiplying the original number by 2, then subtracting \( i \).