Question

If $$\alpha ,\beta ,\gamma $$  and $$a, b, c$$  are complex numbers such that $$\frac{\alpha }{a} + \frac{\beta }{b} + \frac{\gamma }{c} = 1 + i$$     and $$\frac{a}{\alpha } + \frac{b}{\beta } + \frac{c}{\gamma } = 0,$$    then the value of $$\frac{\alpha^2 }{a^2} + \frac{\beta^2 }{b^2} + \frac{\gamma^2 }{c^2}$$   is equal to

A. $$0$$
B. $$- 1$$
C. $$2i$$  
D. $$- 2i$$
Answer :   $$2i$$
Solution :
$$\eqalign{ & \frac{\alpha }{a} + \frac{\beta }{b} + \frac{\gamma }{c} = 1 + i{\text{ squaring}} \cr & \frac{{{\alpha ^2}}}{{{a^2}}} + \frac{{{\beta ^2}}}{{{b^2}}} + \frac{{{\gamma ^2}}}{{{c^2}}} + 2\left( {\frac{{\alpha \beta }}{{ab}} + \frac{{\beta \gamma }}{{bc}} + \frac{{\gamma \alpha }}{{ac}}} \right) = 2i \cr & {\text{or }}\frac{{{\alpha ^2}}}{{{a^2}}} + \frac{{{\beta ^2}}}{{{b^2}}} + \frac{{{\gamma ^2}}}{{{c^2}}} + \frac{{2\alpha \beta \gamma }}{{abc}}\left( {\frac{c}{\gamma } + \frac{a}{\alpha } + \frac{b}{\beta }} \right) = 2i \cr & \therefore \frac{{{\alpha ^2}}}{{{a^2}}} + \frac{{{\beta ^2}}}{{{b^2}}} + \frac{{{\gamma ^2}}}{{{c^2}}} = 2i \cr} $$

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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