Let z ∈ C be such that z < 1 . If ω = 5 + 3 z 5 1 - z , then:

Let zC be such that z<1. If ω=5+3z51-z, then:
  1. 5Reω>1
  2. 5Imω<1
  3. 5Reω>4
  4. 4Imω>5

Solution

Given z<1 and ω=5+3z51-z

5ω1-z=5+3z

5ω-5ωz=5+3z

z=5ω-53+5ω

Using the given condition z=5ω-13+5ω<1


5ω-1<3+5ω

5ω-1<5ω+35

ω-1<ω--35

We know that the locus of a complex number z1 satisfying z1-a=z2-b is the perpendicular bisector of the line segment joining the points a and b.

Hence, the locus of the point ω satisfying ω-1=ω--35 is the line x=1-352=15

Hence, Reω>15

5Reω>1.

Asked in: JEE Main 2019 (09 Apr Shift 2)

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