Math Problem Statement

Find the value of (1 + i√3)^(3/7), (1 - i)^(1/5).

Solution

The problem involves evaluating two expressions with complex numbers:

  1. (1+i3)3/7(1 + i\sqrt{3})^{3/7}
  2. (1i)1/5(1 - i)^{1/5}

Step 1: Express in Polar Form

For complex numbers, it's often convenient to rewrite them in polar form as reiθre^{i\theta}, where:

  • rr is the modulus: r=a2+b2r = \sqrt{a^2 + b^2}
  • θ\theta is the argument: θ=tan1(ba)\theta = \tan^{-1}\left(\frac{b}{a}\right)

For (1+i3)(1 + i\sqrt{3}):

  • r=12+(3)2=1+3=2r = \sqrt{1^2 + (\sqrt{3})^2} = \sqrt{1 + 3} = 2
  • θ=tan1(31)=π3\theta = \tan^{-1}\left(\frac{\sqrt{3}}{1}\right) = \frac{\pi}{3}

So, 1+i3=2eiπ/31 + i\sqrt{3} = 2e^{i\pi/3}.

Raise (1+i3)(1 + i\sqrt{3}) to 37\frac{3}{7}:

(1+i3)3/7=(2eiπ/3)3/7(1 + i\sqrt{3})^{3/7} = \left( 2e^{i\pi/3} \right)^{3/7} Using the power property of complex numbers: r3/7ei(3θ/7)=23/7ei(3π/21)=23/7eiπ/7r^{3/7} e^{i(3\theta/7)} = 2^{3/7} e^{i(3\pi/21)} = 2^{3/7} e^{i\pi/7}


For (1i)(1 - i):

  • r=12+(1)2=2r = \sqrt{1^2 + (-1)^2} = \sqrt{2}
  • θ=tan1(11)=π4\theta = \tan^{-1}\left(\frac{-1}{1}\right) = -\frac{\pi}{4}

So, 1i=2eiπ/41 - i = \sqrt{2}e^{-i\pi/4}.

Raise (1i)(1 - i) to 15\frac{1}{5}:

(1i)1/5=(2eiπ/4)1/5(1 - i)^{1/5} = \left( \sqrt{2}e^{-i\pi/4} \right)^{1/5} Using the power property of complex numbers: r1/5ei(θ/5)=(2)1/5eiπ/20r^{1/5} e^{i(\theta/5)} = (\sqrt{2})^{1/5} e^{-i\pi/20}


Final Results:

  1. (1+i3)3/7=23/7eiπ/7(1 + i\sqrt{3})^{3/7} = 2^{3/7} e^{i\pi/7}
  2. (1i)1/5=(2)1/5eiπ/20(1 - i)^{1/5} = (\sqrt{2})^{1/5} e^{-i\pi/20}

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Polar Form of Complex Numbers
Exponential Representation
Roots and Powers of Complex Numbers

Formulas

Polar Form: z = re^(iθ), where r = √(a² + b²) and θ = tan⁻¹(b/a)
Power of a Complex Number: (re^(iθ))^n = r^n * e^(i * nθ)
Nth Root of a Complex Number: z^(1/n) = r^(1/n) * e^(i(θ + 2kπ)/n), k = 0, 1, ..., n-1

Theorems

Euler's Formula: e^(iθ) = cos(θ) + i*sin(θ)

Suitable Grade Level

Grades 11-12 or College Level