Theory of Equations 1 Question 55

56. If α and β are the roots of the equation x2+px+1=0;γ,δ are the roots of x2+qx+1=0, then q2p2=(αγ)(βγ)(α+δ)(β+δ)

(1978,2M)

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Answer:

Correct Answer: 56. (q2p2)

Solution:

  1. Since, α+β=p,αβ=1 and γ+δ=q,γδ=1

Now, (αγ)(βγ)(α+δ)(β+δ)

=αβγ(α+β)+γ2αβ+δ(α+β)+δ2=1γ(p)+γ21+δ(p)+δ2

=(1+γ2+γp)(1δp+δ2)=(qγ+γp)(δpδq)

[γ2+qγ+1=0 and δ2+qδ+1=0]

=(q2p2)(γδ)=q2p2



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