Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
COMEDK20269 May 2026Evening ShiftMathematicsComplex NumberActual

The conjugate of the multiplicative inverse of the complex number z = 1 + 7i 3 + i is:

Options

  1. A1 + 2i
  2. B1 5 + 2 5 i
  3. C2 5 + 1 5 i
  4. D1 5 - 2 5 i

Correct answer

B. 1 5 + 2 5 i

Step-by-step solution

z = 1 + 7i 3 + i Multiplying the numerator and denominator by the conjugate of the denominator: z = (1 + 7i)(3 - i) (3 + i)(3 - i) z = 3 - i + 21i - 7i^2 3^2 - i^2 z = 3 + 20i + 7 9 + 1 z = 10 + 20i 10 = 1 + 2i The multiplicative inverse of z is 1 z : 1 z = 1 1 + 2i 1 z = 1 - 2i (1 + 2i)(1 - 2i) 1 z = 1 - 2i 1^2 + 2^2 = 1 5 - 2 5 i The conjugate of the multiplicative inverse is: ( 1 z ) = 1 5 + 2 5 i Answer: 1 5 + 2 5 i

Practice Complex Number on Quantrex Academy →

More from Complex Number

If z and are two non-zero complex numbers such that |z |=1 and Arg z- Arg = 2 then z = 2025Let z satisfy |z|=1, z=1- z and Im (z)>0 Statement-I : z is a real number Statement-II : Principal argument of z is 3 . Then 2025If ₁ and ₂ are two non-zero complex numbers and a , b are non zero real numbers such that | a ₁+ b ₂ |= | a ₁- b ₂ | , then ₁ ₂ is 2025If a complex number z=x+i y represents a point P on the Argand plane and Arg ( z-3+2 i z+2-3 i )= 4 , then the locus of P is a 2025By taking a i b =x i y, x>0 , if we get 21+12 2 i 21-12 2 i =a+i b , then b a = 2025Two values of (-8-8 3 i)^ 1 / 4 are 2025If x=3-2 3 i , then x^4-12 x^3+54 x^2-108 x-54= 2025z ₁, z ₂, z ₃ represent the vertices A , B , C of a triangle ABC respectively in the Argand plane. If |z₁-z₂ |= 25-12 3 , | z₁-z₃ z₂-z₃ |= 3 4 and ACB =30^ , then the area (in sq. 2025 Full Complex Number list All COMEDK PYQs