If and are the roots of the equation and if and are the two values of for which the roots and are connected by the relation , what is
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λ ( x 2 − x ) + x + 5 λ x 2 − ( λ − 1 ) x + 5 x 2 − λ λ − 1 x + λ 5 = 0 = 0 = 0
Since α and β are the roots of the equation, by Vieta's formula , we have: α + β = λ λ − 1 and α β = λ 5 . Now,
α + β ( α + β ) 2 α 2 + 2 α β + β 2 α β α 2 + 2 α β + β 2 β α + 2 + α β 2 + 5 4 ⟹ λ 2 − 1 6 λ + 1 = λ λ − 1 = ( λ λ − 1 ) 2 = λ 2 λ 2 − 2 λ + 1 = λ 2 ⋅ λ 5 λ 2 − 2 λ + 1 = 5 λ λ 2 − 2 λ + 1 = 5 λ λ 2 − 2 λ + 1 = 0 Squaring both sides Dividing both sides by α β = λ 5 Given that β α + α β = 5 4 Rearranging
By Vieta's formula, we have λ 1 + λ 2 = 1 6 and λ 1 λ 2 = 1 and λ 2 λ 1 + λ 1 λ 2 = λ 1 λ 2 ( λ 1 + λ 2 ) 2 − 2 = 1 1 6 2 − 2 = 2 5 4 .