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Black Advanced Problems in Mathematics
Exam
Black Advanced Problems in Mathematics
Subject
Mathematics
Chapter
Quadratic Equation

Black Advanced Problems in Mathematics · Mathematics · Quadratic Equation

The range of k for which the inequality k ^2x - k x + 1 ≥ 0 x ∈...

The range of k for which the inequality kcos⁡2x−kcos⁡x+1≥0∀x∈(−∞,∞)k\cos^2x - k\cos x + 1 \ge 0 \forall x \in (-\infty, \infty) is :

Options

  1. Ak>−1/2k > -1/2
  2. Bk>4k > 4
  3. C−1/2≤k≤4-1/2 \le k \le 4
  4. D1/2≤k≤51/2 \le k \le 5.

Correct answer

C. −1/2≤k≤4-1/2 \le k \le 4

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