Question
If α, β ≠ 0 and f(n) = αn+ βn and 
= K(1-α)2(1-β)2(α- β)2, then K is equal to
-
αβ
-
1/αβ
-
1
-
-1
Solution
C.
1
f(n) = αn + βn
f(1) = α + β
f(2) = α2 + β2
f(3) =α3 + β3
f(4) = α4 + β4
Let Δ = 
On expanding, we get
Δ = (1- α2 + (1-β2 )(α-β)2
Δ = K(1-α)2(1-β)2(α- β)2
K=1
