Home
Class 12
MATHS
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

Text Solution

AI Generated Solution

The correct Answer is:
To find the number of solutions of 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 Taking the modulus on both sides, we have: \[ |z^3| = |-\bar{z}| \] Since the modulus of a complex number is always non-negative, we can simplify this to: \[ |z|^3 = |\bar{z}| \] We know that \( |\bar{z}| = |z| \), so we can write: \[ |z|^3 = |z| \] ### Step 3: Solve for modulus Now, we can factor out \( |z| \) (assuming \( |z| \neq 0 \)): \[ |z|^3 - |z| = 0 \] This gives us: \[ |z|(|z|^2 - 1) = 0 \] From this equation, we have two cases: 1. \( |z| = 0 \) 2. \( |z|^2 - 1 = 0 \) which gives \( |z| = 1 \) ### Step 4: Analyze the cases **Case 1**: \( |z| = 0 \) implies \( z = 0 \). This is one solution. **Case 2**: \( |z| = 1 \) means \( z \) lies on the unit circle. We can express \( z \) as: \[ z = e^{i\theta} \] for some angle \( \theta \). ### Step 5: Substitute back into the original equation Substituting \( z = e^{i\theta} \) 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: \[ 4\theta = (2n + 1)\pi \quad \text{for } n \in \mathbb{Z} \] So: \[ \theta = \frac{(2n + 1)\pi}{4} \] ### Step 6: Find the distinct solutions The values of \( n \) will give us distinct angles for \( \theta \): - For \( n = 0 \): \( \theta = \frac{\pi}{4} \) - For \( n = 1 \): \( \theta = \frac{3\pi}{4} \) - For \( n = 2 \): \( \theta = \frac{5\pi}{4} \) - For \( n = 3 \): \( \theta = \frac{7\pi}{4} \) Thus, we have four distinct solutions on the unit circle corresponding to these angles. ### Step 7: Total solutions Including the solution \( z = 0 \), we have a total of: \[ 4 \text{ (from the unit circle)} + 1 \text{ (the zero solution)} = 5 \text{ solutions} \] ### Conclusion The number of solutions of the equation \( z^3 + \bar{z} = 0 \) is **5**. ---

To find the number of solutions of 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: ...
Promotional Banner

Topper's Solved these Questions

  • COMPLEX NUMBERS

    OBJECTIVE RD SHARMA|Exercise Section I - Solved Mcqs|141 Videos
  • COMPLEX NUMBERS

    OBJECTIVE RD SHARMA|Exercise Section II - Assertion Reason Type|15 Videos
  • CIRCLES

    OBJECTIVE RD SHARMA|Exercise Chapter Test|55 Videos
  • CONTINUITY AND DIFFERENTIABILITY

    OBJECTIVE RD SHARMA|Exercise Exercise|86 Videos

Similar Questions

Explore conceptually related problems

The number of jsolutions of the equation z^(2)+barz=0, is

The number of solutions of the equation |z|^(2)+4bar(z)=0 is

The number of solutions of the equation z^(2)=bar(z) is

The number of solutions of the equation z^(3)+(3(barz)^(2))/(|z|)=0 (where, z is a complex number) are

The number of solutions of the equation Im(z^(2))=0,|z|=2 is

OBJECTIVE RD SHARMA-COMPLEX NUMBERS -Chapter Test
  1. The number of solutions of the equation z^(3)+barz=0, is

    Text Solution

    |

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

    Text Solution

    |

  3. If n1, n2 are positive integers, then (1 + i)^(n1) + ( 1 + i^3)^(n1) +...

    Text Solution

    |

  4. The modulus of sqrt(2i)-sqrt(-2i) is

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

  8. If cosA+cosB+cosC=0,sinA + sinB + sinC=0and A+B+C=180^0, then the valu...

    Text Solution

    |

  9. The value of the expression 1.(2-omega).(2-omega^2)+2.(3-omega)(3-omeg...

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

  12. The expression (1+i)^(n1)+(1+i^(3))^(n(2)) is real iff

    Text Solution

    |

  13. |{:("6i " "-3i " "1" ),("4 " " 3i" " -1"),("20 " "3 " " i"):}|=x+iy th...

    Text Solution

    |

  14. The centre of a square ABCD is at z0dot If A is z1 , then the centroid...

    Text Solution

    |

  15. If cosalpha+2cosbeta+3cosgamma=sinalpha+2sinbeta+3singamma=0 and alpha...

    Text Solution

    |

  16. If cosalpha+2cosbeta+3cosgamma=sinalpha+2sinbeta+3singamma=0 and alpha...

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

  21. The vertices of a square are z1,z2,z3 and z4 taken in the anticlockwis...

    Text Solution

    |