JEE Main2014MathematicsComplex NumberActual
If z ₁, z ₂ and z ₃, z ₄ are 2 pairs of complex conjugate numbers, then ( z₁ z₄ )+ ( z₂ z₃ ) equals:
Options
- A0
- B2
- C3 2
Correct answer
A. 0
Step-by-step solution
Consider ( z₁ z₄ )+ ( z₂ z₃ ) = (z₁ )- (z₄ )+ (z₂ )- (z₃ ) aligned &= ( (z₁ )+ (z₂ ) )- ( (z₃ )+ (z₄ ) ) & given ( array l z₂= z ₁ z₄= z ₃ array ) &= ( (z₁ )+ ( z ₁ ) )- ( (z₃ )+ ( z ₃ ) ) & array l also ( ( z ₁ )=- (z₁ ) . ( z ₃ )=- (z₃ ) array &= ( (z₁ )- (z₁ ) )- ( (z₃ )- (z₃ ) ) &=0-0=0 aligned