Let $\mathrm{z}_{1}$ and $\mathrm{z}_{2}$ be any two non-zero complex numbers such that $3\left|z_{1}\right|=4\left|z_{2}\right|$.
If $\mathrm{z}=\frac{3 \mathrm{z}_{1}}{2 \mathrm{z}_{2}}+\frac{2 \mathrm{z}_{2}}{3 \mathrm{z}_{1}}$ then :
$|\mathrm{z}|=\frac{1}{2} \sqrt{\frac{17}{2}}$
$\operatorname{Re}(z)=0$
$|\mathrm{z}|=\sqrt{\frac{5}{2}}$
$\operatorname{Im}(z)=0$
Correct Option: , 4
$3\left|z_{1}\right|=4\left|z_{2}\right|$
$\Rightarrow \frac{\left|z_{1}\right|}{\left|z_{2}\right|}=\frac{4}{3}$
$\Rightarrow \frac{\left|3 z_{1}\right|}{\left|2 z_{2}\right|}=2$
Let $\frac{3 \mathrm{z}_{1}}{2 \mathrm{z}_{2}}=\mathrm{a}=2 \cos \theta+2 \mathrm{i} \sin \theta$
$\mathrm{z}=\frac{3 \mathrm{z}_{1}}{2 \mathrm{z}_{2}}+\frac{2 \mathrm{z}_{2}}{3 \mathrm{z}_{1}}=\mathrm{a}+\frac{1}{\mathrm{a}}$
$=\frac{5}{2} \cos \theta+\frac{3}{2} i \sin \theta$
Now all options are incorrect
Remark :
There is a misprint in the problem actual problem should be :
"Let $z_{1}$ and $z_{2}$ be any non-zero complex number such that $3\left|z_{1}\right|=2\left|z_{2}\right|$.
If $\mathrm{z}=\frac{3 \mathrm{z}_{1}}{2 \mathrm{z}_{2}}+\frac{2 \mathrm{z}_{2}}{3 \mathrm{z}_{1}}$, then"
Given
$3\left|z_{1}\right|=2\left|z_{2}\right|$
Now $\left|\frac{3 z_{1}}{2 z_{2}}\right|=1$
Let $\frac{3 z_{1}}{2 z_{2}}=a=\cos \theta+i \sin \theta$
$\mathrm{z}=\frac{3 \mathrm{z}_{1}}{2 \mathrm{z}_{2}}+\frac{2 \mathrm{z}_{2}}{3 \mathrm{z}_{1}}$
$=a+\frac{1}{a}=2 \cos \theta$
$\therefore \quad \operatorname{Im}(z)=0$
Now option (4) is correct.
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All Study Material
- JEE Main
- Exam Pattern
- Previous Year Papers
- PYQ Chapterwise
- Physics
- Kinematics 1D
- Kinemetics 2D
- Friction
- Work, Power, Energy
- Centre of Mass and Collision
- Rotational Dynamics
- Gravitation
- Calorimetry
- Elasticity
- Thermal Expansion
- Heat Transfer
- Kinetic Theory of Gases
- Thermodynamics
- Simple Harmonic Motion
- Wave on String
- Sound waves
- Fluid Mechanics
- Electrostatics
- Current Electricity
- Capacitor
- Magnetism and Matter
- Electromagnetic Induction
- Atomic Structure
- Dual Nature of Matter
- Nuclear Physics
- Radioactivity
- Semiconductors
- Communication System
- Error in Measurement & instruments
- Alternating Current
- Electromagnetic Waves
- Wave Optics
- X-Rays
- All Subjects
- Physics
- Motion in a Plane
- Law of Motion
- Work, Energy and Power
- Systems of Particles and Rotational Motion
- Gravitation
- Mechanical Properties of Solids
- Mechanical Properties of Fluids
- Thermal Properties of matter
- Thermodynamics
- Kinetic Theory
- Oscillations
- Waves
- Electric Charge and Fields
- Electrostatic Potential and Capacitance
- Current Electricity
- Thermoelectric Effects of Electric Current
- Heating Effects of Electric Current
- Moving Charges and Magnetism
- Magnetism and Matter
- Electromagnetic Induction
- Alternating Current
- Electromagnetic Wave
- Ray Optics and Optical Instruments
- Wave Optics
- Dual Nature of Radiation and Matter
- Atoms
- Nuclei
- Semiconductor Electronics: Materials, Devices and Simple Circuits.
- Chemical Effects of Electric Current,