If α, β and γ are the roots of the equation x3 - 3 x2 + 5x - 9 = 0 then the value of the expression
( α + β - γ) ( β + γ -α) (γ + α - β).
Solution: Given equation x3 - 3 x2 + 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