Complex Numbers 2 Question 1

1. The equation |zi|=|z1|,i=1, represents

(a) a circle of radius 12 (2019 Main, 12 April I)

(b) the line passing through the origin with slope 1

(c) a circle of radius 1

(d) the line passing through the origin with slope -1

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Answer:

Correct Answer: 1. (b)

Solution:

  1. Let the complex number z=x+iy

Also given, |zi|=|z1|

|x+iyi|=|x+iy1|x2+(y1)2=(x1)2+y2

[|z|=(Re(z))2+(Im(z))2]

On squaring both sides, we get

x2+y22y+1=x2+y22x+1

y=x, which represents a line through the origin with slope 1.



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