Complex Number Exponents
What are Complex Number Exponents?
Complex number exponents involve raising a complex number to a power. This operation combines concepts from complex numbers and exponentiation, resulting in a new complex number.
Formula
The formula for complex number exponents uses De Moivre's theorem:
\[ (r(\cos\theta + i\sin\theta))^n = r^n(\cos(n\theta) + i\sin(n\theta)) \]
Where:
\(r\) is the magnitude of the complex number
\(\theta\) is the argument (angle) of the complex number
\(n\) is the exponent
\(i\) is the imaginary unit (\(\sqrt{-1}\))
Calculation Steps
Let's calculate (2 + 3i)^4:
Express in polar form:
\(r = \sqrt{2^2 + 3^2} = \sqrt{13}\)
\(\theta = \tan^{-1}(\frac{3}{2}) \approx 0.9828\)
Apply De Moivre's formula:
\((\sqrt{13}(\cos 0.9828 + i\sin 0.9828))^4\)
Calculate:
\(r^4 = (\sqrt{13})^4 = 13^2 = 169\)
\(4\theta = 4 \times 0.9828 \approx 3.9312\)
Result:
\(169(\cos 3.9312 + i\sin 3.9312)\)
\(\approx -119 - 120i\)
Example and Visual Representation
Let's visualize (2 + 3i)^4:
Re
Im
θ
nθ
This visual representation shows:
The original complex number 2+3i in blue
The result (2+3i)^4 ≈ -119-120i in red
The original angle θ in green
The new angle 4θ in orange