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JEE Main
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Basics of Mathematics

JEE Main · Mathematics · Basics of Mathematics

Number of integers satisfying the inequality,& x^ 4 - 29x^ 2 + 100...

Number of integers satisfying the inequality,& x4−29x2+100≤0x^{4} - 29x^{2} + 100 \le 0& is

Options

  1. A22
  2. B44
  3. C66
  4. D88

Correct answer

D. 88

Step-by-step solution

We have,& x4−29x2+100≤0x^{4} - 29x^{2} + 100 \le 0.

⇒x4−25x2−4x2+100≤0⇒ x^{4} - 25x^{2} - 4x^{2} + 100 \le 0

⇒(x2−4)(x2−25)≤0⇒ \left(x^{2} - 4\right)\left(x^{2} - 25\right) \le 0

⇒4≤x2≤25⇒ 4 \le x^{2} \le 25

or~\left(x - 2\right)\left(x + 2\right)\left(x - 5\right)\left(x + 5\right) \le 0</p><p>Bywavycurvemethodandusingsignschemeforthisinequality,</p><p></p><p>By wavy curve method and using sign scheme for this inequality,</p><p>⇒ x \in \left[-5, - 2\right] \cup \left[2, 5\right]

Integers satisfying above are ±5,±4,±3,±2.</p><p>So,thereareeightintegers.</p></blockquote>\pm5, \pm4, \pm3, \pm2.</p><p>So, there are eight integers.</p></blockquote>

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