Math Problem Statement

Z⁴ = (1-i)/(1+i√3)

Solution

We are tasked with solving the equation Z4=1i1+i3Z^4 = \frac{1 - i}{1 + i\sqrt{3}}.

Step 1: Express the right-hand side in polar form

First, we want to express the complex fraction on the right-hand side in polar form. To do this, let's break down the numerator and denominator:

  • Numerator: 1i1 - i

    • The modulus of 1i1 - i is given by: 1i=12+(1)2=2|1 - i| = \sqrt{1^2 + (-1)^2} = \sqrt{2}
    • The argument of 1i1 - i (in radians) is: arg(1i)=tan1(11)=π4\arg(1 - i) = \tan^{-1}\left(\frac{-1}{1}\right) = -\frac{\pi}{4} Therefore, in polar form, 1i=2eiπ/41 - i = \sqrt{2} e^{-i\pi/4}.
  • Denominator: 1+i31 + i\sqrt{3}

    • The modulus of 1+i31 + i\sqrt{3} is: 1+i3=12+(3)2=4=2|1 + i\sqrt{3}| = \sqrt{1^2 + (\sqrt{3})^2} = \sqrt{4} = 2
    • The argument of 1+i31 + i\sqrt{3} is: arg(1+i3)=tan1(31)=π3\arg(1 + i\sqrt{3}) = \tan^{-1}\left(\frac{\sqrt{3}}{1}\right) = \frac{\pi}{3} Therefore, in polar form, 1+i3=2eiπ/31 + i\sqrt{3} = 2 e^{i\pi/3}.

Step 2: Simplify the complex fraction

Now we rewrite the right-hand side of the equation using these polar forms: 1i1+i3=2eiπ/42eiπ/3=22ei(π4π3)\frac{1 - i}{1 + i\sqrt{3}} = \frac{\sqrt{2} e^{-i\pi/4}}{2 e^{i\pi/3}} = \frac{\sqrt{2}}{2} e^{i\left(-\frac{\pi}{4} - \frac{\pi}{3}\right)} Simplify the exponent: π4π3=3π124π12=7π12-\frac{\pi}{4} - \frac{\pi}{3} = -\frac{3\pi}{12} - \frac{4\pi}{12} = -\frac{7\pi}{12} Thus, the equation becomes: Z4=22ei7π/12Z^4 = \frac{\sqrt{2}}{2} e^{-i7\pi/12}

Step 3: Solve for ZZ

Now, we take the fourth root of both sides. To find the fourth roots of a complex number in polar form, we use the formula: Zk=r1/4ei(θ+2kπ4)Z_k = r^{1/4} e^{i \left(\frac{\theta + 2k\pi}{4}\right)} where r=22r = \frac{\sqrt{2}}{2} and θ=7π12\theta = -\frac{7\pi}{12}, and k=0,1,2,3k = 0, 1, 2, 3.

  • The modulus of ZkZ_k is: r1/4=(22)1/4=21/8r^{1/4} = \left(\frac{\sqrt{2}}{2}\right)^{1/4} = 2^{-1/8}

  • The argument of ZkZ_k is: 7π12+2kπ4=7π+24kπ48=(24k7)π48\frac{-\frac{7\pi}{12} + 2k\pi}{4} = \frac{-7\pi + 24k\pi}{48} = \frac{(24k - 7)\pi}{48}

Thus, the four solutions are: Zk=21/8ei(24k7)π48,k=0,1,2,3Z_k = 2^{-1/8} e^{i\frac{(24k - 7)\pi}{48}}, \quad k = 0, 1, 2, 3

Final Answer:

The four solutions for ZZ are: Z0=21/8ei7π48,Z1=21/8ei17π48,Z2=21/8ei41π48,Z3=21/8ei65π48Z_0 = 2^{-1/8} e^{i\frac{-7\pi}{48}}, \quad Z_1 = 2^{-1/8} e^{i\frac{17\pi}{48}}, \quad Z_2 = 2^{-1/8} e^{i\frac{41\pi}{48}}, \quad Z_3 = 2^{-1/8} e^{i\frac{65\pi}{48}}

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Related Questions:

  1. How do you convert a complex number into polar form?
  2. What is the significance of taking roots of complex numbers in polar form?
  3. How do you find the argument of a complex number geometrically?
  4. What are the practical applications of finding the roots of complex numbers?
  5. How do you perform multiplication and division of complex numbers in polar form?

Tip: Always convert complex numbers to polar form for easier multiplication, division, and root extraction!

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Polar Form
Roots of Complex Numbers

Formulas

Polar form of complex numbers: r e^(iθ)
Formula for nth roots of complex numbers: Z_k = r^(1/n) e^(i(θ + 2kπ)/n)

Theorems

De Moivre's Theorem
Polar Form of Complex Numbers

Suitable Grade Level

Grades 11-12