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📐 Mathematics  ·  Complex Numbers and Quadratic Equations  ·  JEE

How many complex numbers z satisfy both |z| = 1 and z = z-bar?

Answer: 2.

  • A 0
  • B 1
  • C 2
  • D Infinitely many

Correct answer: C. 2

Explanation: z=z̄ means the imaginary part of z is 0, so z must be real. Combined with |z|=1: z∈R and |z|=1 gives z=1 or z=-1. Check: |1|=1✓, 1̄=1✓; |-1|=1✓, (-1̄)=-1✓. Exactly 2 solutions. Answer: 2 complex numbers

Argand Plane: z = a + ibReImz = a+iba (real part)b (imaginary part)θ = arg(z)|z| = length of the vector OZ = √(a²+b²); θ = angle OZ makes with the positive real axis

A complex number z = a+ib is plotted as a point (or vector from the origin) on the Argand plane, with the real part along the horizontal axis and the imaginary part along the vertical; its modulus |z| is the vector's length, and its argument θ is the angle from the positive real axis.

Concept context

Complex numbers in a+ib form, modulus, argument, polar form, cube roots of unity, and quadratic equations with complex roots

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