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MathsMediumNumerical2021 Β· 25 Jul Shift 1

Q81.If 𝛼, 𝛽 are roots of the equation π‘₯2 + 5√2π‘₯+ 10 = 0, 𝛼> 𝛽 and 𝑃𝑛= 𝛼𝑛- 𝛽𝑛 for each positive integer 𝑛, then the value of 𝑃17𝑃20 + 5√2𝑃17𝑃192 is equal to 𝑃18𝑃19 + 5√2𝑃18

What This Question Tests

This question tests the ability to derive and apply a recurrence relation for Pn = αⁿ - βⁿ based on the given quadratic equation and then simplify the given expression.

Concepts Tested

Roots of quadratic equationRecurrence relationsAlgebraic manipulation

Formulas Used

If α, β are roots of ax²+bx+c=0, then Pn = αⁿ - βⁿ satisfies aPn + bPn-1 + cPn-2 = 0

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