Powers and roots of complex numbers

1003118406

Level: 
C
All the solutions of the equation \( x^4+1+\sqrt3\mathrm{i} = 0 \) are complex numbers, whose arguments are from the interval \( [0; 2\pi) \). Find the sum of the arguments of all the solutions of the equation.
\( \frac{13}3\pi \)
\( 4\pi \)
\( \frac{25}6\pi \)
\( \frac92\pi \)

1003118405

Level: 
C
All the solutions of the equation \( x^6-4\sqrt3+4\mathrm{i} = 0 \) can be displayed as points in the rectangular coordinate system. What is the distance of the two most distant points?
\( 2\sqrt2 \)
\( \sqrt2 \)
\( 2\sqrt[3]4 \)
\( \sqrt[3]4 \)
\( 2\sqrt3 \)
\( \sqrt3 \)

1103118404

Level: 
C
Consider an equation \( x^n+b=0 \), where \( n \) is a positive integer and \( b \) is a complex number. In the picture the points that correspond to the roots of the equation are depicted in black. Find the equation.
\( x^3 + 4\sqrt2 - 4\sqrt2\mathrm{i} = 0 \)
\( x^3 + 4\sqrt2 +4\sqrt2\mathrm{i} = 0 \)
\( x^3 - 4\sqrt2 - 4\sqrt2\mathrm{i} = 0 \)
\( x^3 - 4\sqrt2 +4\sqrt2\mathrm{i} = 0 \)

1003118402

Level: 
C
Which of the given complex numbers is not a root of the equation \( x^6 + 8\mathrm{i} = 0 \)?
\( 1-\mathrm{i} \)
\( 1+\mathrm{i} \)
\( -1-\mathrm{i} \)
\( \sqrt2\left(\cos\frac{7\pi}{12}+\mathrm{i}\cdot\sin\frac{7\pi}{12}\right) \)
\( \sqrt2\left(\cos\frac{23\pi}{12}+\mathrm{i}\cdot\sin\frac{23\pi}{12}\right) \)

1003118401

Level: 
C
Find the solution set of the equation \( x^3 - 8\mathrm{i} = 0 \) in the set of complex numbers.
\( \left\{\sqrt3+\mathrm{i}; -\sqrt3+\mathrm{i};-2\mathrm{i} \right\} \)
\( \left\{ 2\mathrm{i}; -\sqrt3-\mathrm{i}; \sqrt3-\mathrm{i} \right\} \)
\( \left\{\frac{\sqrt3}2+\frac12\mathrm{i}; -\frac{\sqrt3}2+\frac12\mathrm{i};-\mathrm{i} \right\} \)
\( \left\{\mathrm{i};-\frac{\sqrt3}2-\frac12\mathrm{i}; \frac{\sqrt3}2-\frac12\mathrm{i} \right\} \)

1003123402

Level: 
A
Given the complex number \( b=\sqrt[3]2\cdot\left(\cos\frac56\pi+\mathrm{i}\cdot\sin\frac56\pi\right) \), find the polar form of \( b^9 \).
\( 8\cdot\left(\cos\frac32\pi+\mathrm{i}\cdot\sin\frac32\pi\right) \)
\( 64\cdot\left(\cos\frac12\pi-\mathrm{i}\cdot\sin\frac12\pi\right) \)
\( 8\cdot\left(\cos\frac12\pi-\mathrm{i}\cdot\sin\frac12\pi\right) \)
\( 64\cdot\left(\cos\frac32\pi+\mathrm{i}\cdot\sin\frac32\pi\right) \)

1003123401

Level: 
A
Given the complex number \( a =\sqrt3\cdot\left( \cos 225^{\circ} + \mathrm{i}\cdot\sin 225^{\circ}\right) \), find the polar form of \( a^6 \).
\( 27\cdot\left(\cos270^{\circ}+\mathrm{i}\cdot\sin270^{\circ}\right) \)
\( 9\cdot\left(\cos90^{\circ}+\mathrm{i}\cdot\sin90^{\circ}\right) \)
\( 27\cdot\left(\cos90^{\circ}+\mathrm{i}\cdot\sin90^{\circ}\right) \)
\( 9\cdot\left(\cos270^{\circ}+\mathrm{i}\cdot\sin270^{\circ}\right) \)

1003109305

Level: 
B
Solve the following equation in the set of complex numbers. (Solve the equation by substitution.) \[ (2x + 3)^4 - 256 = 0 \]
\( \left\{-\frac72;\frac12;-\frac32\pm2\mathrm{i} \right\} \)
\( \left\{-\frac72;\frac12;\frac32\pm2\mathrm{i} \right\} \)
\( \left\{\frac72;-\frac12;\frac32\pm2\mathrm{i} \right\} \)
\( \left\{\frac72;-\frac12;-\frac32\pm2\mathrm{i} \right\} \)