If α , β are the roots of the equation, x 2 - x - 1 = 0 and S n = 2023 α n + 2024 β n , then

If α,β are the roots of the equation, x2-x-1=0 and Sn=2023αn+2024βn, then
  1. 2 S12=S11+S10
  2. S12=S11+S10
  3. 2 S11=S12+S10
  4. S11=S10+S12

Solution

Given: α, β are roots of x2-x-1=0.

α2-α-1=0

α2=α+1   ...i

Also, Sn=2023αn+2024βn

Sn-1+Sn-2=2023αn-1+2024βn-1+2023αn-2+2024βn-2

Sn-1+Sn-2=2023αn-21+α+2024βn-21+β

Using equation i,

Sn-1+Sn-2=2023αn-2α2+2024βn-2β2

Sn-1+Sn-2=2023αn+2024βn

Sn-1+Sn-2=Sn

Putting, n=12

S12=S11+S10

Asked in: JEE Main 2024 (27 Jan Shift 2)

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