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

Let z 1 and z 2 be any two non-zero complex numbers such that 3 z 1 = 4 z 2 . If z = 3 z 1 2 z 2 + 2 z 2 3 z 1 then maximum value of z is Note: In actual paper value of z was asked. Hence, none of the options given were correct. So we have modified the question as well as options.

Options

  1. A7 2
  2. B9 2
  3. C5 2
  4. D1 2 17 2

Correct answer

C. 5 2

Step-by-step solution

Let a r g 3 z 1 2 z 2 = θ , and we know that, if the a r g z = α , then a r g 1 z = - α . ∴   a r g 2 z 2 3 z 1 = - θ Also, we know that a complex number w can be expressed as w = w cos α + i sin α , where α is the argument of the complex number. ∴   z = 3 2 z 1 z 2 cos θ + i sin θ + 2 3 z 2 z 1 cos θ - i sin θ Given, 3 z 1 = 4 z 2 ,     ⇒ z 1 z 2 = 4 3 , ⇒ z = 3 2 × 4 3 cos θ + i sin θ + 2 3 × 3 4

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