Question:medium

The number of integral solution of \(\frac{x + 1}{x^2 + 2}>\frac{1}{4}\) is

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Check denominator positive: \(x^2 + 2>0\) always.
Updated On: Jun 16, 2026
  • 1
  • 2
  • 5
  • None of these
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The Correct Option is C

Solution and Explanation

Let's solve the inequality given in the problem: \(\frac{x + 1}{x^2 + 2} > \frac{1}{4}\). We want to find the number of integral solutions for this inequality.

First, we'll set the inequality by cross-multiplying to clear the fractions:

\(4(x + 1) > x^2 + 2\)

Expand and simplify the inequality:

\(4x + 4 > x^2 + 2\)

\(4x + 4 - 2 > x^2\)

\(4x + 2 > x^2\)

\(-x^2 + 4x + 2 > 0\) or equivalently \(x^2 - 4x - 2 < 0\).

Find the roots of the quadratic equation \(x^2 - 4x - 2 = 0\) using the quadratic formula \(x = \frac{{-b \pm \sqrt{{b^2 - 4ac}}}}{2a}\), where \(a = 1\)\(b = -4\), and \(c = -2\):

Discriminant: \(b^2 - 4ac = 16 + 8 = 24\)

Roots: \(x = \frac{{4 \pm \sqrt{24}}}{2} = \frac{{4 \pm 2\sqrt{6}}}{2} = 2 \pm \sqrt{6}\)

Identify the range where the quadratic inequality is true:

Since \(x^2 - 4x - 2 < 0\) is a parabola opening upwards, solutions for the inequality are between the roots \(2 - \sqrt{6} < x < 2 + \sqrt{6}\).

Numerically, \(2 - \sqrt{6} \approx -0.449\) and \(2 + \sqrt{6} \approx 4.449\).

Determine integer solutions within this range:

Integer values of \(x\) within this range are 0, 1, 2, 3, 4, making 5 solutions.

Thus, the number of integral solutions is 5. This matches the correct answer.

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