Mathematics · Complex Numbers

JEE Main 2024 — 9 April, Shift 1 — Question 22

The sum of the square of the modulus of the elements in the set

{z=a+ib:a, b∈Z,z∈C,∣z−1∣≤1,∣z−5∣≤∣z−5i∣}\{\mathrm{z}=\mathrm{a}+\mathrm{ib}: \mathrm{a}, \mathrm{~b} \in \mathrm{Z}, \mathrm{z} \in \mathrm{C},|\mathrm{z}-1| \leq 1,|\mathrm{z}-5| \leq|\mathrm{z}-5 \mathrm{i}|\} is \qquad

Answer: 9

Numerical answer — enter this value.

Step-by-step solution

∣z−1∣≤1|z-1| \leq 1 ⇒∣(x−1)+iy∣≤1\Rightarrow|(\mathrm{x}-1)+\mathrm{iy}| \leq 1

⇒(x−1)2+y2≤1\Rightarrow \sqrt{(\mathrm{x}-1)^{2}+\mathrm{y}^{2}} \leq 1

⇒(x−1)2+y2≤1\Rightarrow(\mathrm{x}-1)^{2}+\mathrm{y}^{2} \leq 1

\qquad Also ∣z−5∣≤∣z−5i∣|z-5| \leq|z-5 i|

(x−5)2+y2≤x2+(y−5)2(x-5)^{2}+y^{2} \leq x^{2}+(y-5)^{2}

−10x≤−10y-10 x \leq-10 y ⇒x≥y\Rightarrow x \geq y Solving (1) and (2)

⇒(x−1)2+x2=1\Rightarrow(\mathrm{x}-1)^{2}+\mathrm{x}^{2}=1

⇒2x2−2x=0\Rightarrow 2 \mathrm{x}^{2}-2 \mathrm{x}=0

⇒x(x−1)=0\Rightarrow \mathrm{x}(\mathrm{x}-1)=0

⇒x=0\Rightarrow \mathrm{x}=0 or x=1\mathrm{x}=1

y=0 or y=1\mathrm{y}=0 \text { or } \mathrm{y}=1

figure

Given x,y∈I\mathrm{x}, \mathrm{y} \in \mathrm{I}

Points (0,0),(1,0),(2,0),(1,1),(1,−1)(0,0),(1,0),(2,0),(1,1),(1,-1) to find ∣z1∣2+∣z2∣2+∣z3∣2+∣z4∣2+∣z5∣2\left|\mathrm{z}_{1}\right|^{2}+\left|\mathrm{z}_{2}\right|^{2}+\left|\mathrm{z}_{3}\right|^{2}+\left|\mathrm{z}_{4}\right|^{2}+\left|\mathrm{z}_{5}\right|^{2}

=0+1+4+2+2=9=0+1+4+2+2=9

Answer key and solution verified before publishing.

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Exam
JEE Main 2024
Subject
Mathematics
Chapter
Complex Numbers
Topic
Geometry of Complex Numbers
The sum of the square of the modulus of the elements in the set \ z =… | JEE Main 2024 PYQ with Solution · DhiX AI