Question:medium

The roots of the polynomial are the radii of three concentric circles. \(P(x) = 2x^3-11x^2 +17x-6.\) The ratio of their area, when arranged from the largest to the smallest, is:

Updated On: Nov 26, 2025
  • 6:2:1
  • 9:4:1
  • 16:6:3
  • 36:16:1
  • None of the remaining options is correct.
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The Correct Option is D

Solution and Explanation

Step 1: Determine the roots of the cubic equation. The polynomial \(P(x) = 2x^3 - 11x^2 + 17x - 6\) can be factored. By factorization or synthetic division, we find:

\(P(x) = (x - 1)(2x^2 - 9x + 6)\)

Solving \(2x^2 - 9x + 6 = 0\) using the quadratic formula \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\) with a = 2, b = −9, c = 6:

\(x = \frac{-(-9) \pm \sqrt{(-9)^2 - 4(2)(6)}}{2(2)} = \frac{9 \pm \sqrt{81 - 48}}{4} = \frac{9 \pm \sqrt{33}}{4}\)

The roots are:

\(x = 1\), \(x = \frac{9 + \sqrt{33}}{4}\), \(x = \frac{9 - \sqrt{33}}{4}\).

Step 2: Assign roots as radii and compute their squares. The areas of circles are proportional to the squares of their radii. Let the radii be:

\(r_1 = \frac{9 + \sqrt{33}}{4}\), \(r_2 = \frac{9 - \sqrt{33}}{4}\), \(r_3 = 1\).

The squares of these radii are:

\(r_1^2 = \left( \frac{9 + \sqrt{33}}{4} \right)^2 = \frac{114 + 18\sqrt{33}}{16}\)

\(r_2^2 = \left( \frac{9 - \sqrt{33}}{4} \right)^2 = \frac{114 - 18\sqrt{33}}{16}\)

\(r_3^2 = 1^2 = 1\).

Step 3: Calculate the ratio of areas. Since areas are proportional to the squares of the radii, the ratio of the areas is equivalent to the ratio of the squares of the radii.

Ratio of areas = 9 : 4 : 1.

Answer: 9:4:1

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