JEE Main 2019MathematicsComplex NumberMediumMCQ

JEE Main 2019 — Complex Number Question with Solution

JEE Main 2019 (10 Apr Shift 1)

Question

If a>0 and z=(1+i)2a-i , has magnitude 25 , then z- is equal to:

Choose an option

Show full solutionCorrect option: A
Correct answer
A-15-35i

Step-by-step explanation

Z=1+i2a-i=2ia-i
z=25⇒2ia-i=2a2+1=25
⇒a=3   ∵a>0
So, z-=2i3-i-= -2i3+i=-2i3+i×3-i3-i
=-6i-232+1=-15-35i

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About this question

This is a previous-year question from JEE Main 2019, covering the Complex Number chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.