If the point (λ, λ + 1) lies inside the region bounded by the curve and y - axis, then λ belongs to the interval

Given that the point (λ, λ + 1) lies inside the region bounded by the curve and y - axis.



The curve is rewritten as,


x2 = 25 - y2


x2 + y2 = 25


S = x2 + y2 - 25


We know that for a point (a, b) to lie inside the circle S, the condition to be satisfied is S11<0.


Applying S11<0 for 1st circle,


λ2 + (λ + 1)2 - 25<0


λ2 + λ2 + 2λ + 1 - 25<0


2 + 2λ - 24<0


λ2 + λ - 12<0


λ2 + 4λ - 3λ - 12<0


λ(λ + 4) - 3(λ + 4)<0


(λ - 3)(λ + 4)<0


We know that the solution set of (x - a)(x - b)<0 for b>a is (a,b).


The solution set for λ is (- 4,3) ...... (1)


Since the point lies inside y - axis λ + 1>0


λ> - 1 ..... (2)


The resultant solution set is the intersection of (1) and (2).


λ((- 4,3)(- 1,∞))


λ(- 1,3)


The correct option is (a).

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