Question

If $${\left( {a + ib} \right)^5} = \alpha + i\beta $$     then $${\left( {b + ia} \right)^5}$$  is equal to

A. $$\beta + i\alpha $$  
B. $$ \alpha - i\beta $$
C. $$\beta - i\alpha $$
D. $$ - \alpha - i\beta $$
Answer :   $$\beta + i\alpha $$
Solution :
$${\left( {b + ia} \right)^5} = {i^5}{\left( {a - ib} \right)^5} = i\left( {\alpha - i\beta } \right).$$

Releted MCQ Question on
Algebra >> Complex Number

Releted Question 1

If the cube roots of unity are $$1,\omega ,{\omega ^2},$$  then the roots of the equation $${\left( {x - 1} \right)^3} + 8 = 0\,\,{\text{are}}$$

A. $$ - 1,1 + 2\omega ,1 + 2{\omega ^2}$$
B. $$ - 1,1 - 2\omega ,1 - 2{\omega ^2}$$
C. $$- 1, - 1, - 1$$
D. none of these
Releted Question 2

The smallest positive integer $$n$$ for which $${\left( {\frac{{1 + i}}{{1 - i}}} \right)^n} = 1\,{\text{is}}$$

A. $$n = 8$$
B. $$n = 16$$
C. $$n = 12$$
D. none of these
Releted Question 3

The complex numbers $$z = x+ iy$$   which satisfy the equation $$\left| {\frac{{z - 5i}}{{z + 5i}}} \right| = 1$$   lie on

A. the $$x$$ - axis
B. the straight line $$y = 5$$
C. a circle passing through the origin
D. none of these
Releted Question 4

If $$z = {\left( {\frac{{\sqrt 3 }}{2} + \frac{i}{2}} \right)^5} + {\left( {\frac{{\sqrt 3 }}{2} - \frac{i}{2}} \right)^5},\,{\text{then}}$$

A. $${\text{Re}}\left( z \right) = 0$$
B. $${\text{Im}}\left( z \right) = 0$$
C. $${\text{Re}}\left( z \right) > 0,{\text{Im}}\left( z \right) > 0$$
D. $${\text{Re}}\left( z \right) > 0,{\text{Im}}\left( z \right) < 0$$

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Complex Number


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