Question Details

If α, β are the roots of the equation, x2 – x – 1 and Sn = 2023 αn + 2024 βn, then :

Options

A

S12 = S11 + S10

B

2S11 = S12 + S10

C

2S12 = S11 + S10

D

S11 = S10 + S12

Show Answer

Correct Answer :

Option A

S12 = S11 + S10

S12 = S11 + S10

Solution :

The correct option is S12 = S11 + S10.

Here is the step-by-step mathematical derivation:

Step 1: Understand the properties of the roots of the quadratic equation.
The given quadratic equation is:
x2x1=0
Since α and β are the roots of this equation, they must satisfy it. Therefore, we have:
α2α1=0α2=α+1
and
β2β1=0β2=β+1

Step 2: Find a general recurrence relation for the powers of the roots.
Multiply the equation for α by αn on both sides:
αn+2=αn+1+αn
Similarly, multiply the equation for β by βn on both sides:
βn+2=βn+1+βn

Step 3: Relate these equations to the definition of Sn.
We are given the definition:
Sn=2023αn+2024βn
Let us write the expression for Sn+2:
Sn+2=2023αn+2+2024βn+2
Substitute the relations derived in Step 2:
Sn+2=2023(αn+1+αn)+2024(βn+1+βn)
Group the terms by their powers:
Sn+2=(2023αn+1+2024βn+1)+(2023αn+2024βn)
Using the definition of Sn, this simplifies to the recurrence relation:
Sn+2=Sn+1+Sn

Step 4: Substitute the value n = 10.
By substituting n=10 into our recurrence relation, we get:
S12=S11+S10

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