[JEE Main 2011] let alpha beta be real and z complex if z 2 alpha z beta
Let $\alpha,\beta$ be real and $z$ complex. If $z^2+\alpha z+\beta=0$ has two distinct roots on the line $\operatorname{Re}z=1$, then it is necessary that
(a) $\beta\in(-1,0)$
(b) $|\beta|=1$
(c) $\beta\in(1,\infty)$
(d) $\beta\in(0,1)$
1 Answer
Correct answer: (c) $\beta\in(1,\infty)$
Distinct roots on $\operatorname{Re}z=1$ must be conjugates $1\pm it$ ($t\ne0$), so $\beta=$ product $=1+t^2>1$, i.e. $\beta\in(1,\infty)$.
JEE Main 2011 · Complex Numbers — verified solution by the Vidaara Team.
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