Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main201910 Apr 2019Morning ShiftMathematicsComplex NumberActual

If a > 0 and z = ( 1 + i ) 2 a - i , has magnitude 2 5 , then z - is equal to:

Options

  1. A- 1 5 - 3 5 i
  2. B- 3 5 - 1 5 i
  3. C1 5 - 3 5 i
  4. D- 1 5 + 3 5 i

Correct answer

A. - 1 5 - 3 5 i

Step-by-step solution

Z = 1 + i 2 a - i = 2 i a - i z = 2 5 ⇒ 2 i a - i = 2 a 2 + 1 = 2 5 ⇒ a = 3       ∵ a > 0 So, z - = 2 i 3 - i - =   - 2 i 3 + i = - 2 i 3 + i × 3 - i 3 - i = - 6 i - 2 3 2 + 1 = - 1 5 - 3 5 i

Practice Complex Number on Quantrex Academy →

More from Complex Number

The number of values of z C , satisfying the equations |z-(4+8i)|= 10 and |z-(3+5i)|+|z-(5+11i)|=4 5 , is: 2026Let S = z C : z^2 + 6 ,iz - 3 = 0 . Then _ z S z^8 is equal to : 2026Let the set of all values of k R such that the equation z( z + 2 + i) + k(2 + 3i) = 0 , z C , has at least one solution, be the interval [ , ] . Then 9( + ) is equal to: 2026Let z₁, z₂ C be the distinct solutions of the equation z^2 + 4z - (1 + 12i) = 0 . Then |z₁|^2 + |z₂|^2 is equal to : 2026Let S= z C : z^2+4z+16=0 . Then _ z S |z+ 3 i|^2 is equal to: 2026Let z be a complex number such that |z+2| = |z-2| and ( z+3 z-i ) = 4 . Then |z|^2 is equal to: 2026Let the circles C₁ : |z| = r and C₂ : |z - 3 - 4i| = 5 , z C , be such that C₂ lies within C₁ . If z₁ moves on C₁ , z₂ moves on C₂ and |z₁ - z₂| = 2 , then |z₁ - z₂| is equal to: 2026Let x and y be real numbers such that 50 ( 2x 1+3i - y 1-2i ) = 31 + 17i , i = -1 . Then the value of 10(x - 3y) is : 2026 Full Complex Number list All JEE Main PYQs