If α , β be roots of x 2 – 3x + a = 0 and γ, δ be roots of x 2 – 12x + b = 0 and α , β , γ, δ , (in order) form an increasing G.P. Then
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since α , β be roots of x 2 – 3x + a = 0
∴ α + β = 3, αβ = a
since γ , δ be roots of x 2 – 12x + b = 0
∴ γ + δ = 12, γδ = b
= 
⇒
= 
= 
16a = b
Let r be the common ratio of α , β , γ , δ
then β = α r, γ = α r 2 and δ = α r 3 α and β be roots of equation x
2 – 3x + a = 0
∴ α + β = α (1 + r) = 3 .........(i)
αβ = α ( α r) = a ..........(ii)
γ and δ be roots of equation x 2 – 12x + b = 0
∴ γ + δ = α r 2 (1 + r) = 12 ........(iii)
γδ = ( α r 2 ) ( α r 3 ) = b ⇒ α 2 r 5 = b ........(iv)
from (iii) ÷ (i) r 2 = 4 ⇒ r = 2
then from (i), α = 1 ⇒ a = 2
b = 2 5 =32
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