Join WhatsApp Icon JEE WhatsApp Group
Question 61

If $$z \neq 0$$ be a complex number such that $$\left|z - \frac{1}{z}\right| = 2$$, then the maximum value of $$|z|$$ is

We have a complex number $$z \neq 0$$ satisfying $$\left|z - \dfrac{1}{z}\right| = 2$$, and we need to find the maximum value of $$|z|$$.

We use the reverse triangle inequality. We know that $$\left|z - \dfrac{1}{z}\right| \geq \bigg||z| - \dfrac{1}{|z|}\bigg|$$. Since $$\left|z - \dfrac{1}{z}\right| = 2$$, we get $$\bigg||z| - \dfrac{1}{|z|}\bigg| \leq 2$$.

Now let $$r = |z|$$. We need $$\left|r - \dfrac{1}{r}\right| \leq 2$$, which gives us $$-2 \leq r - \dfrac{1}{r} \leq 2$$.

We focus on the upper bound $$r - \dfrac{1}{r} \leq 2$$. Multiplying by $$r > 0$$, we get $$r^2 - 2r - 1 \leq 0$$. Using the quadratic formula, $$r \leq \dfrac{2 + \sqrt{4+4}}{2} = 1 + \sqrt{2} = \sqrt{2} + 1$$.

We need to verify this maximum is achievable. If $$z = r$$ is a positive real number with $$r = \sqrt{2}+1$$, then $$\dfrac{1}{r} = \dfrac{1}{\sqrt{2}+1} = \sqrt{2}-1$$, so $$z - \dfrac{1}{z} = (\sqrt{2}+1) - (\sqrt{2}-1) = 2$$. This satisfies the given condition, confirming the maximum is attained.

Hence, the correct answer is Option D: $$\sqrt{2}+1$$.

Get AI Help

Video Solution

video

Create a FREE account and get:

  • Free JEE Mains Previous Papers PDF
  • Take JEE Mains paper tests

JEE Quant Questions | JEE Quantitative Ability

JEE DILR Questions | LRDI Questions For JEE

JEE Verbal Ability Questions | VARC Questions For JEE

Free JEE Topicwise Questions

JEE Rotational MotionJEE Units & MeasurementsJEE Atomic StructureJEE GravitationJEE Periodic Table & PeriodicityJEE StatisticsJEE Inverse Trigonometric FunctionsJEE Magnetism & Magnetic MaterialsJEE Sequences & SeriesJEE MatricesJEE Alternating CurrentsJEE Carboxylic AcidsJEE Permutations & CombinationsJEE Work, Energy & PowerJEE Electromagnetic InductionJEE Electronic DevicesJEE d and f-Block ElementsJEE Chemical KineticsJEE Heat TransferJEE Three Dimensional GeometryJEE Magnetic Effects of CurrentJEE Hydrocarbons - AromaticJEE Electromagnetic WavesJEE Aldehydes & KetonesJEE Hydrocarbons - AlkanesJEE Applications of DerivativesJEE EquilibriumJEE Indefinite IntegrationJEE Chemical ThermodynamicsJEE ElectrochemistryJEE ProbabilityJEE BiomoleculesJEE Continuity & DifferentiabilityJEE Kinetic Theory of GasesJEE Vector AlgebraJEE Hydrocarbons - AlkynesJEE Differential EquationsJEE Current & ResistanceJEE Straight LinesJEE WavesJEE Redox ReactionsJEE Hydrocarbons - AlkenesJEE DeterminantsJEE SolutionsJEE Ray OpticsJEE Dual Nature of Matter & RadiationJEE Chemical Bonding & Molecular StructureJEE Complex NumbersJEE Sets, Relations & FunctionsJEE Electric Charges & FieldsJEE Laws of MotionJEE Fluid MechanicsJEE Basic Concepts in ChemistryJEE Trigonometric FunctionsJEE LimitsJEE Laws of ThermodynamicsJEE Kinematics - 2D MotionJEE p-Block Elements (Groups 13-18)JEE Simple Harmonic MotionJEE Electric Potential & CapacitanceJEE Coordination CompoundsJEE JEE 2D GeometryJEE CirclesJEE Definite IntegrationJEE EMF & Circuit AnalysisJEE Surface TensionJEE Atoms & NucleiJEE Laboratory Experiments - XIJEE Number SystemJEE Basic Principles of Organic ChemistryJEE Wave OpticsJEE Quadratic EquationsJEE Alcohols, Phenols & EthersJEE Organic Compounds with HalogensJEE DifferentiationJEE Conic SectionsJEE Nitrogen-Containing CompoundsJEE ElasticityJEE Practical Organic ChemistryJEE Kinematics - 1D MotionJEE Purification & CharacterisationJEE Binomial Theorem
Ask AI