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TS EAMCET · Maths · Quadratic Equation

The set of all values of \(x\) which satisfy both the inequations \(x^2-1 \leq 0\) and \(x^2-x-2 \geq 0\) simultaneously is

  1. A \((-1,2)\)
  2. B \((-1,1)\)
  3. C \((-2,-1)\)
  4. D \(\{-1\}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\{-1\}\)

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \text { (d) } \quad x^2-1 \leq 0 \Rightarrow(x+1)(x-1) \leq 0 \\ & \therefore \quad x \in[-1,1\} \\ & x^2-x-2 \geq 0 \Rightarrow(x-2)(x+1) \geq 0 \\ & \therefore \quad x \in(-\infty,-1] \cup[2, \infty) \\ & \therefore \quad x \in\{-1\} .\end{aligned}\)