Most Important Selected Qs for JEE AdvancedMathematicsComplex Number
Paragraph: In argand plane consider A ( z ₁ ), B ( z ₂ ) and C ( z ₃ ) as distinct complex numbers lying on the curve | z ^2 |= 3 . Question: If a root of z₁ z^2+z₂ z+z₃=0 has modulus unity then z₁, z₂, z₃ are in
Options
- AA.P.
- BG.P.
- CH.P.
- Dall of above
Correct answer
B. G.P.
Step-by-step solution
Let z_ , z_p be roots of the equation z₁ z^2+z₂ z+z₃=0 such that |z_d |=1 then (z_ +z_ )⁻=z_ z_ ( -z₂ z₁ )⁻= z₃ z₁ z₂^2=z₁ z₃ Hence z₁, z₂, z₃ are in G.P. Since z₁^2+z₂^2+z₃^2=z₁ z₂+z₂ z₃+z₃ z₁ A B C is equilateral. Also PA ^2+ PB ^2+ PC ^2=3 |z₁ |^2- (1+ + ^2 ) z₁^ z - (1+ + ^2 ) z₁ z+ |z₁ |^2+ |z₁ |^2+ |z₁ |^2=6 r^2=18 .