Chapter 17: Problem 12
Express the given function in the form \(f(z)=u+i v\) $$ f(z)=z^{4} $$
Short Answer
Expert verified
The function can be expressed as: \(f(z) = (x^4 - 6x^2y^2 + y^4) + i(4x^3y - 4xy^3)\).
Step by step solution
01
Express the Complex Number
Let the complex number be represented as \(z = x + iy\), where \(x\) is the real part and \(y\) is the imaginary part.
02
Compute the Function
We need to find \(f(z) = (x + iy)^4\). Begin by expanding \((x + iy)^4\) using the binomial expansion theorem.
03
Apply Binomial Theorem
The binomial expansion of \((x + iy)^4\) is given by: \[ (x + iy)^4 = x^4 + 4x^3(iy) + 6x^2(iy)^2 + 4x(iy)^3 + (iy)^4 \]
04
Simplify Terms
Calculate each term in the expansion:- \(x^4\) remains as is.- \(4x^3(iy) = 4ix^3y\).- \(6x^2(iy)^2 = -6x^2y^2\) because \((i^2 = -1)\).- \(4x(iy)^3 = -4ixy^3\) because \((i^3 = -i)\).- \((iy)^4 = y^4\) because \((i^4 = 1)\).
05
Combine Real and Imaginary Parts
Combine all terms to separate real and imaginary parts:\[(x^4 - 6x^2y^2 + y^4) + i(4x^3y - 4xy^3)\]Here, \(u = x^4 - 6x^2y^2 + y^4\) and \(v = 4x^3y - 4xy^3\).
06
Express Function in Required Form
Write the function in the form \(f(z) = u + iv\):\[f(z) = (x^4 - 6x^2y^2 + y^4) + i(4x^3y - 4xy^3)\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Binomial Expansion
The binomial expansion is a crucial mathematical method used to expand expressions raised to a power. It's especially significant when dealing with powers involving complex terms. In our exercise, the function \[ f(z) = (x + iy)^4 \]is expanded using the binomial theorem.The binomial theorem provides a formula to expand expressions of the form \((a + b)^n\). For \((x + iy)^4\),we apply this theorem to break down the expression into a series of terms:
- \(x^4\)
- \(4x^3(iy)\)
- \(6x^2(iy)^2\)
- \(4x(iy)^3\)
- \((iy)^4\)
Imaginary and Real Parts
To fully understand complex functions, it's essential to distinguish between their real and imaginary parts. Complex numbers are represented in the form \(z = x + iy\),where \(x\) is the real part and \(y\) is the imaginary part.
In our example of expanding \((x + iy)^4\),we identified and simplified each term using imaginary unit \(i\),where \(i^2 = -1\).Then, we categorized these terms into real and imaginary components:
In our example of expanding \((x + iy)^4\),we identified and simplified each term using imaginary unit \(i\),where \(i^2 = -1\).Then, we categorized these terms into real and imaginary components:
- Real part, \(u\): \(x^4 - 6x^2y^2 + y^4\)
- Imaginary part, \(v\): \(4x^3y - 4xy^3\)
Complex Numbers
Complex numbers are fundamental in advanced mathematics, often used to solve real-world problems involving waves, oscillations, and other phenomena where two dimensions are needed.
A complex number, expressed as \(z = x + iy\),combines a real part \(x\) and an imaginary part \(y\). Imaginary numbers, characterized by the symbol \(i\) where \(i = \sqrt{-1}\),allow numbers to exist beyond the conventional real-number line.Key aspects:
A complex number, expressed as \(z = x + iy\),combines a real part \(x\) and an imaginary part \(y\). Imaginary numbers, characterized by the symbol \(i\) where \(i = \sqrt{-1}\),allow numbers to exist beyond the conventional real-number line.Key aspects:
- The real part \(x\) can be seen on a horizontal axis, while the imaginary part \(y\) appears on a vertical axis in the complex plane.
- Complex numbers can be represented, assessed, and manipulated using algebraic operations like addition and multiplication.
- When raising complex numbers to a power, as done in our exercise, the results require careful separation into real and imaginary components.