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The number of solutions of the equation ...

The number of solutions of the equation `z^(3)+barz=0`, is

A

2

B

3

C

4

D

5

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The correct Answer is:
To solve the equation \( z^3 + \bar{z} = 0 \), we will follow these steps: ### Step 1: Rewrite the equation We start with the equation: \[ z^3 + \bar{z} = 0 \] This can be rewritten as: \[ z^3 = -\bar{z} \] ### Step 2: Take the modulus of both sides Taking the modulus of both sides, we have: \[ |z^3| = |-\bar{z}| \] Since the modulus of a complex number is always non-negative, we can simplify this to: \[ |z^3| = |\bar{z}| \] Using the property that \( |\bar{z}| = |z| \), we can write: \[ |z|^3 = |z| \] ### Step 3: Analyze the modulus equation From the equation \( |z|^3 = |z| \), we can factor it as: \[ |z|^3 - |z| = 0 \] Factoring gives: \[ |z|(|z|^2 - 1) = 0 \] This leads to two cases: 1. \( |z| = 0 \) 2. \( |z|^2 - 1 = 0 \) which gives \( |z| = 1 \) ### Step 4: Solve for \( |z| = 0 \) If \( |z| = 0 \), then: \[ z = 0 \] This is one solution. ### Step 5: Solve for \( |z| = 1 \) If \( |z| = 1 \), we can express \( z \) in polar form as: \[ z = e^{i\theta} \] Substituting this into the original equation: \[ (e^{i\theta})^3 + \bar{e^{i\theta}} = 0 \] This simplifies to: \[ e^{3i\theta} + e^{-i\theta} = 0 \] Multiplying through by \( e^{i\theta} \) gives: \[ e^{4i\theta} + 1 = 0 \] Thus: \[ e^{4i\theta} = -1 \] This implies: \[ 4\theta = (2n + 1)\pi \quad \text{for } n \in \mathbb{Z} \] Solving for \( \theta \): \[ \theta = \frac{(2n + 1)\pi}{4} \] This gives us four distinct angles for \( n = 0, 1, 2, 3 \): - \( \theta = \frac{\pi}{4} \) - \( \theta = \frac{3\pi}{4} \) - \( \theta = \frac{5\pi}{4} \) - \( \theta = \frac{7\pi}{4} \) ### Step 6: Count the total solutions From \( |z| = 0 \), we have 1 solution: \( z = 0 \). From \( |z| = 1 \), we have 4 solutions corresponding to the angles above. Thus, the total number of solutions is: \[ 1 + 4 = 5 \] ### Final Answer The number of solutions of the equation \( z^3 + \bar{z} = 0 \) is \( \boxed{5} \). ---

To solve the equation \( z^3 + \bar{z} = 0 \), we will follow these steps: ### Step 1: Rewrite the equation We start with the equation: \[ z^3 + \bar{z} = 0 \] This can be rewritten as: ...
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OBJECTIVE RD SHARMA ENGLISH-COMPLEX NUMBERS -Chapter Test
  1. The number of solutions of the equation z^(3)+barz=0, is

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  2. The locus of the center of a circle which touches the circles |z-z1|=a...

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  3. Prove that for positive integers n(1) and n(2), the value of express...

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  4. The value of abs(sqrt( 2i) - sqrt(2i)) is :

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  5. Prove that the triangle formed by the points 1,(1+i)/(sqrt(2)),a n di ...

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  6. The value of ((1+ i sqrt(3))/(1-isqrt(3)))+ ((1-isqrt(3))/(1+isqrt(3)...

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  7. If alpha+ibeta=tan^(-1) (z), z=x+iy and alpha is constant, the locus o...

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  8. If cosA+cosB+cosC=0,sinA+sinB+sinC=0andA+B+C=180^(@) then the value of...

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  9. Find the sum 1xx(2-omega)xx(2-omega^(2))+2xx(-3-omega)xx(3-omega^(2))+...

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  10. The value of the expression (1+(1)/(omega))+(1+(1)/(omega^(2)))+(2+(1)...

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  11. The condition that x^(n+1)-x^(n)+1 shall be divisible by x^(2)-x+1 is ...

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  12. The expression (1+i)^(n1)+(1+i^(3))^(n2) is real iff

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  13. If |{:(6i,3i,1),(4,3i,-1),(20,3,i):}|=x+iy, then (x, y) is equal to

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  14. If cosalpha+2cosbeta+3cosgamma=sinalpha+2sinbeta+3singamma=0,t h e nt ...

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  15. If cosalpha+2cosbeta+3cosgamma=sinalpha+2sinbeta+3singamma=0,t h e nt ...

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  16. Sum of the series sum(r=0)^n (-1)^r ^nCr[i^(5r)+i^(6r)+i^(7r)+i^(8r)] ...

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  17. If az(1)+bz(2)+cz(3)=0 for complex numbers z(1),z(2),z(3) and real num...

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  18. If 2z1-3z2 + z3=0, then z1, z2 and z3 are represented by

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  19. If Re((z+4)/(2z-1)) = 1/2 then z is represented by a point lying on

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  20. The vertices of a square are z(1),z(2),z(3) and z(4) taken in the anti...

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  21. Let lambda in R . If the origin and the non-real roots of 2z^2+2z+lam...

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