Math Problem Statement

解答下这些题目

解答下这些题目

Solution

I can see the examination card with multiple math problems. Let's work through them one by one. I'll provide the steps for each solution:


1. Evaluate z=(3+i)6z = (\sqrt{3} + i)^6

To evaluate this, we can convert the complex number z=3+iz = \sqrt{3} + i to polar form.

  • The modulus of zz is: z=(3)2+12=3+1=4=2|z| = \sqrt{(\sqrt{3})^2 + 1^2} = \sqrt{3 + 1} = \sqrt{4} = 2
  • The argument of zz, θ\theta, is: θ=tan1(13)=π6\theta = \tan^{-1}\left(\frac{1}{\sqrt{3}}\right) = \frac{\pi}{6}

Now, express zz in polar form: z=2(cosπ6+isinπ6)z = 2\left(\cos\frac{\pi}{6} + i \sin\frac{\pi}{6}\right)

To evaluate z6z^6, use De Moivre’s Theorem: z6=26(cos(6×π6)+isin(6×π6))=64(cosπ+isinπ)z^6 = 2^6 \left( \cos\left(6 \times \frac{\pi}{6}\right) + i \sin\left(6 \times \frac{\pi}{6}\right) \right) = 64 \left( \cos \pi + i \sin \pi \right) Since cosπ=1\cos \pi = -1 and sinπ=0\sin \pi = 0, we get: z6=64×(1)=64z^6 = 64 \times (-1) = -64

2. Graphically represent the set of values of zz for which 1z31 \leq |z| \leq 3, Im z1z \geq 1

This problem describes a region in the complex plane:

  • The modulus of zz, z|z|, must lie between 1 and 3, which corresponds to a circular annular region with inner radius 1 and outer radius 3.
  • The imaginary part of zz, Im(z)\text{Im}(z), must be greater than or equal to 1, meaning the region is above the line Im(z)=1\text{Im}(z) = 1.

This can be visualized as a ring between two circles (radius 1 and radius 3), limited to the upper half-plane above Im(z)=1\text{Im}(z) = 1.

3. Solve the equation z2i=0z^2 - i = 0

Rearrange the equation: z2=iz^2 = i

To solve for zz, express ii in polar form: i=eiπ2i = e^{i\frac{\pi}{2}}

Thus, z2=eiπ2z^2 = e^{i\frac{\pi}{2}}, and the general solution for zz is: z=eiπ4+inπ2forn=0,1z = e^{i\frac{\pi}{4} + i\frac{n\pi}{2}} \quad \text{for} \quad n = 0, 1

The two solutions are: z=eiπ4orz=ei5π4z = e^{i\frac{\pi}{4}} \quad \text{or} \quad z = e^{i\frac{5\pi}{4}} In rectangular form: z=22+i22orz=22i22z = \frac{\sqrt{2}}{2} + i\frac{\sqrt{2}}{2} \quad \text{or} \quad z = -\frac{\sqrt{2}}{2} - i\frac{\sqrt{2}}{2}


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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Polar Representation
Analytic Functions
Residue Theorem
Definite Integrals
Ordinary Differential Equations

Formulas

De Moivre's Theorem: (r(cos θ + i sin θ))^n = r^n(cos(nθ) + i sin(nθ))
Residue Formula: Residue = lim_(z→z0) (z-z0)f(z)
Integral formula for parametric curves
Second-order differential equations

Theorems

De Moivre's Theorem
Cauchy-Riemann Equations
Residue Theorem

Suitable Grade Level

University Level