Question:

The locus of z such that  \(\frac{|z-i|}{|z+i|}\)= 2, where z = x+iy. is

Updated On: Aug 21, 2024
  • 3x2 + 3y2 +10y + 3

  • 3x2 - 3y2 - 10y - 3 = 0

  • 3x2 + 3y2 + 10y + 3 = 0

  • x2 + y2 - 5y + 3 = 0

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The Correct Option is C

Solution and Explanation

The correct option is: (A): 3x2 + 3y2 + 10y + 3 = 0.

Given: ∣zi∣=2∣z+i

Hence: ∣​2zi​∣∣​2=∣∣​1z+i​∣∣​2

This simplifies to: x2+(y−1)2=4(x2+(y+1)2)

Further simplifying: 3x2+4(y+1)2−(y−1)2=0

And: 3x2+3y2+8y+2y+4−1=0

Finally: 3x2 + 3y2 + 10y + 3 = 0.

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Concepts Used:

Complex Number

A Complex Number is written in the form

a + ib

where,

  • “a” is a real number
  • “b” is an imaginary number

The Complex Number consists of a symbol “i” which satisfies the condition i^2 = −1. Complex Numbers are mentioned as the extension of one-dimensional number lines. In a complex plane, a Complex Number indicated as a + bi is usually represented in the form of the point (a, b). We have to pay attention that a Complex Number with absolutely no real part, such as – i, -5i, etc, is called purely imaginary. Also, a Complex Number with perfectly no imaginary part is known as a real number.