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TS EAMCET · Maths · Quadratic Equation

Let \(S\) be the set of all possible integral values of \(\lambda\) in the interval \((-3,7)\) for which the roots of the quadratic equation \(\lambda x^2+13 x+7=0\) are all rational numbers. Then the sum of the elements in \(S\) is

  1. A 4
  2. B 2
  3. C 3
  4. D 1
Verified Solution

Answer & Solution

Correct Answer

(A) 4

Step-by-step Solution

Detailed explanation

We have, \(\begin{aligned} & \lambda x^2+13 x+7 & =0 \\ \therefore & D & =(13)^2-4(\lambda)(7)=169-28 \lambda \end{aligned}\) \(\therefore \quad D=(13)^2-4(\lambda)(7)\) So, \(\lambda \in(-3,7)\) has values \(-2,0,6\) so that \(D\) become perfect square. \(\therefore\) Required…