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← JEE Main 2022 · 29 Jul · Shift 2
MathematicsSingle correct+4 / -1Question 17 of 90

JEE Main 2022 · 29 Jul · Shift 2, Mathematics question 17

Let S={z=x+iy:∣z−1+i∣≥∣z∣, ∣z∣<2, ∣z+i∣=∣z−1∣}S=\left\{z=x+iy:|z-1+i|\ge|z|,\ |z|<2,\ |z+i|=|z-1|\right\}. Then the set of all values of xx, for which w=2x+iy∈Sw=2x+iy\in S for some y∈Ry\in\mathbb R, is

Choose one option
Answer and worked solution

Official answer: B

Conditions. ∣z−1+i∣≥∣z∣|z-1+i|\ge|z| is y≥x−1y\ge x-1; ∣z+i∣=∣z−1∣|z+i|=|z-1| is y=−xy=-x.

For w = 2x + iy: y=−2xy=-2x, then −2x≥2x−1-2x\ge2x-1 gives x≤14x\le\frac14, and ∣w∣2=8x2<4|w|^2=8x^2<4 gives ∣x∣<12|x|<\frac1{\sqrt2}.

(B)