If α,β and γ are the roots of the equation x3−3x2+5x−9=0 then the value of the expression
(α+β−γ)(β+γ−α)(γ+α−β).
Solution: Given equation x3−3x2+5x−9=0
α+β+γ=3 or ∑α=3
αβ+βγ+γα=5
αβγ=9
(α+β−γ)(β+γ−α)(γ+α−β)
⇒(∑α−2γ)(∑α−2α)(∑α−2β)
(3−2γ)(3−2α)(3−2β)
=(9−6α−6γ+4αγ)(3−2β)
=(9−6α−6γ+4αγ)(3−2β)
=(27−18β−18α+12αβ−18γ+12γβ+12αγ−8αβγ
=27−18×3+12×5−8×9
=27−54+60−72
=−39