Q.
Let p,q,r∈R and r>p>0. If the quadratic equation px2+qx+r=0 has two complex roots α and β, then ∣α∣+∣β∣ is
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AIEEEAIEEE 2012Complex Numbers and Quadratic Equations
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Solution:
Given quadratic equation is px2+qcx+r=0...(1) D=q2−4pr
Since α and β are two complex root ∴β=αˉ⇒∣β∣=∣αˉ∣⇒∣β∣=∣α∣ (∵∣αˉ∣=∣α∣)
Consider ∣α∣+∣β∣=∣α∣+∣α∣(∵∣β∣=∣α∣) =2∣α∣>2.1=2(∵∣αˉ∣>1)
Hence, ∣α∣+∣β∣ is greater than 2.