Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main20208 Jan 2020Evening ShiftMathematicsComplex NumberActual

Let α = - 1 + i 3 2 . If a = 1 + α ∑ k = 0 100 α 2 k and b = ∑ k = 0 100 α 3 k , then a and b , are the roots of the quadratic equation.

Options

  1. Ax 2 + 101 x + 100 = 0
  2. Bx 2 - 102 x + 101 = 0
  3. Cx 2 - 101 x + 100 = 0
  4. Dx 2 + 102 x + 101 = 0

Correct answer

B. x 2 - 102 x + 101 = 0

Step-by-step solution

Given, α = - 1 + i 3 2 a = 1 + α ∑ k = 0 100 α 2 k and b = ∑ k = 0 100 α 3 k Now α = ω     ;   ω = - 1 + i 3 2 Using this a and b can be written as a = 1 + ω 1 + ω 2 + ω 4 + … ω 198 + ω 200 = 1 + ω 1 - ω 2 101 1 - ω 2 = 1 + ω 1 - ω 1 - ω 2 = 1 Similarly, b = 1 + ω 3 + ω 6 + … + ω 300 = 101 So, the required quadratic equation is x 2 - a + b x + a b = 0 ⇒ x 2 - 102 x +

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