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The values of lamda for which one root o...

The values of `lamda` for which one root of the equation `x^2+(1-2lamda)x+(lamda^2-lamda-2)=0` is greater than 3 and the other smaller than 2 are given by

A

`2ltlamdalt5`

B

`1ltlamdalt4`

C

`1ltlamdalt5`

D

`2ltlamdalt4`

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To solve the problem, we need to find the values of \(\lambda\) for which one root of the quadratic equation \[ x^2 + (1 - 2\lambda)x + (\lambda^2 - \lambda - 2) = 0 \] is greater than 3 and the other root is smaller than 2. ### Step 1: Identify the quadratic function The given quadratic function can be expressed as: \[ f(x) = x^2 + (1 - 2\lambda)x + (\lambda^2 - \lambda - 2) \] ### Step 2: Determine conditions for roots Since the parabola opens upwards (as the coefficient of \(x^2\) is positive), we need to ensure that: - \(f(2) < 0\) (indicating one root is less than 2) - \(f(3) < 0\) (indicating the other root is greater than 3) ### Step 3: Calculate \(f(2)\) Substituting \(x = 2\) into the function: \[ f(2) = 2^2 + (1 - 2\lambda) \cdot 2 + (\lambda^2 - \lambda - 2) \] Calculating this gives: \[ f(2) = 4 + (2 - 4\lambda) + (\lambda^2 - \lambda - 2) \] \[ = \lambda^2 - 5\lambda + 6 < 0 \] ### Step 4: Factor the quadratic inequality We can factor the quadratic: \[ \lambda^2 - 5\lambda + 6 = (\lambda - 2)(\lambda - 3) < 0 \] ### Step 5: Solve the inequality The roots of the quadratic are \(\lambda = 2\) and \(\lambda = 3\). The inequality \((\lambda - 2)(\lambda - 3) < 0\) holds true for: \[ 2 < \lambda < 3 \] ### Step 6: Calculate \(f(3)\) Now substituting \(x = 3\) into the function: \[ f(3) = 3^2 + (1 - 2\lambda) \cdot 3 + (\lambda^2 - \lambda - 2) \] Calculating this gives: \[ f(3) = 9 + (3 - 6\lambda) + (\lambda^2 - \lambda - 2) \] \[ = \lambda^2 - 7\lambda + 10 < 0 \] ### Step 7: Factor the second quadratic inequality We can factor the quadratic: \[ \lambda^2 - 7\lambda + 10 = (\lambda - 2)(\lambda - 5) < 0 \] ### Step 8: Solve the second inequality The roots of this quadratic are \(\lambda = 2\) and \(\lambda = 5\). The inequality \((\lambda - 2)(\lambda - 5) < 0\) holds true for: \[ 2 < \lambda < 5 \] ### Step 9: Find the intersection of both conditions From the two inequalities we have: 1. \(2 < \lambda < 3\) 2. \(2 < \lambda < 5\) The intersection of these two conditions is: \[ 2 < \lambda < 3 \] ### Conclusion Thus, the values of \(\lambda\) for which one root is greater than 3 and the other is smaller than 2 are: \[ \lambda \in (2, 3) \]
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