Location of Roots When Compared with a Constant 'k'
Let a, b, c ∈...
Question
Let a,b,c∈R and a≠0. If α is a root of a2x2+bx+c=0,β is a root of a2x2−bx−c=0 and 0<α<β, then the equation, a2x2+2bx+2c=0 has a root γ that always satisfies
A
γ=β
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B
α<γ<β
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C
γ=(α+β)/2
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D
γ=α
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Solution
The correct option is Bα<γ<β Let f(x)=a2x2+2bx+2c
From the question, a2α2+bα+c=0anda2β2−bβ−c=0
Now, f(α)=a2α2+2bα+2c=bα+c=−a2α2f(β)=a2β2+2bβ+2c=3(bβ+c)=3a2β2
but 0<α<β ⇒αandβ are Positive. ∴f(α)<0,f(β)>0
Hence, α<γ<β.