Mathematics - Quadratic Equation Question with Solution | TestHub

MathematicsQuadratic EquationTheory of equationsMedium2 minPYQ_2021

MathematicsMediumsingle choice

If $α, β \in R$ are such that $1 - 2 i$ (here $i^{2} = - 1$ ) is a root of $z^{2} + α z + β = 0$ , then $(α - β)$ is equal to:

Answer:

Solution:

$∵ α, β \in R \Rightarrow$ other root is $1 + 2 i$

$α = -$ ( sum of roots ) $= - (1 - 2 i + 1 + 2 i) = - 2$

$β =$ product of roots $= (1 - 2 i) (1 + 2 i) = 5$

$∴ α - β = - 7$

option $(1)$

Stream:JEESubject:MathematicsTopic:Quadratic EquationSubtopic:Theory of equations

⏱ 2mℹ️ Source: PYQ_2021

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