Math Problem Statement

Determine the algebraic form of the following complex numbers: z1 = (2 + 2i)^6 and z2 = ((1 + i√3) / (1 - i))^20.

Solution

To determine the algebraic form of the complex numbers z1=(2+2i)6z_1 = (2 + 2i)^6 and z2=(1+i31i)20z_2 = \left( \frac{1 + i \sqrt{3}}{1 - i} \right)^{20}, we can approach each problem by using polar form and De Moivre's theorem.

Solution for z1=(2+2i)6z_1 = (2 + 2i)^6:

  1. Convert 2+2i2 + 2i to polar form:

    • Find the modulus rr of 2+2i2 + 2i: r=2+2i=22+22=8=22r = |2 + 2i| = \sqrt{2^2 + 2^2} = \sqrt{8} = 2\sqrt{2}
    • Find the argument θ\theta: θ=tan1(22)=tan1(1)=π4\theta = \tan^{-1}\left(\frac{2}{2}\right) = \tan^{-1}(1) = \frac{\pi}{4}
    • Therefore, in polar form: 2+2i=22(cosπ4+isinπ4)2 + 2i = 2\sqrt{2} \left(\cos \frac{\pi}{4} + i \sin \frac{\pi}{4}\right)
  2. Apply De Moivre's theorem:

    • Since z1=(2+2i)6z_1 = (2 + 2i)^6, we raise both the modulus and the argument to the power of 6: z1=(22)6(cos(6π4)+isin(6π4))z_1 = (2\sqrt{2})^6 \left(\cos\left(6 \cdot \frac{\pi}{4}\right) + i \sin\left(6 \cdot \frac{\pi}{4}\right)\right)
    • Calculate (22)6(2\sqrt{2})^6: (22)6=64(2\sqrt{2})^6 = 64
    • Simplify the argument 6π4=3π26 \cdot \frac{\pi}{4} = \frac{3\pi}{2}: z1=64(cos3π2+isin3π2)z_1 = 64 \left(\cos \frac{3\pi}{2} + i \sin \frac{3\pi}{2}\right)
    • Since cos3π2=0\cos \frac{3\pi}{2} = 0 and sin3π2=1\sin \frac{3\pi}{2} = -1: z1=64(0i)=64iz_1 = 64 \cdot (0 - i) = -64i

Thus, z1=64iz_1 = -64i.

Solution for z2=(1+i31i)20z_2 = \left( \frac{1 + i \sqrt{3}}{1 - i} \right)^{20}:

  1. Simplify 1+i31i\frac{1 + i \sqrt{3}}{1 - i}:
    • To simplify, multiply the numerator and denominator by the conjugate of the denominator, 1+i1 + i: 1+i31i1+i1+i=(1+i3)(1+i)(1i)(1+i)\frac{1 + i \sqrt{3}}{1 - i} \cdot \frac{1 + i}{1 + i} = \frac{(1 + i \sqrt{3})(1 + i)}{(1 - i)(1 + i)}
    • Calculate the denominator: (1i)(1+i)=12(1)=2(1 - i)(1 + i) = 1^2 - (-1) = 2
    • Expand the numerator: [ (1 + i \sqrt{3})(1 + i) = 1 + i + i \sqrt{3} - \sqrt{3} = (1 - \sqrt{3}) + i (1 + \sqrt{3}) \

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Polar Form
Exponents

Formulas

Modulus of a complex number: |a + bi| = √(a^2 + b^2)
Argument of a complex number: θ = tan^(-1)(b/a)
De Moivre's Theorem: (r(cos θ + i sin θ))^n = r^n(cos(nθ) + i sin(nθ))

Theorems

De Moivre's Theorem

Suitable Grade Level

Grade 12 or College-level