If t1 and t2 are the roots of the equation t2+λt+1=0, where λ is a parameter, then the line joining the points (at21,2at1) and (at22,2at2) always passes through
A
(a,0)
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B
(−a,0)
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C
(λ,0)
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D
(−λ,0)
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Solution
The correct option is B(−a,0) Since t1 and t2 are the roots of the given equation, ∴t1+t2=−λ⋯(1)
and t1t2=1⋯(2)
Equation of the line joining the given points is y−2at1=2at2−2at1at22−at21(x−at21)⇒y(t1+t2)=2x+2at1t2
Using equation (1) and (2), −λy=2x+2a⇒y=(−2λ)(x+a)
The above line always passes through (−a,0).