NDA Math Mock Test 03 – Question 18

Question:

The eccentricity of the hyperbola \(16x^2 – 9y^2 = 1\) is:

अतिपरवलय \(16x^2 – 9y^2 = 1\) की उत्केंद्रता (eccentricity) है:

Options:

  • 3/5
  • 5/3
  • 4/5
  • 5/4
  • 3/5
  • 5/3
  • 4/5
  • 5/4

Correct Answer: b)

Explanation:

Writing the hyperbola in standard form \(\frac{x^2}{a^2} – \frac{y^2}{b^2} = 1\):
\[\frac{x^2}{(1/16)} – \frac{y^2}{(1/9)} = 1 \implies a^2 = \frac{1}{16}, \; b^2 = \frac{1}{9}\]
The eccentricity \(e\) of a hyperbola is given by:
\[e = \sqrt{1 + \frac{b^2}{a^2}} = \sqrt{1 + \frac{1/9}{1/16}} = \sqrt{1 + \frac{16}{9}} = \sqrt{\frac{25}{9}} = \frac{5}{3}\]
Hence, the correct option is (b).

अतिपरवलय को मानक रूप \(\frac{x^2}{a^2} – \frac{y^2}{b^2} = 1\) में लिखने पर:
\[a^2 = \frac{1}{16}, \quad b^2 = \frac{1}{9}\]
उत्केंद्रता \(e\) का सूत्र:
\[e = \sqrt{1 + \frac{b^2}{a^2}} = \sqrt{1 + \frac{1/9}{1/16}} = \sqrt{1 + \frac{16}{9}} = \sqrt{\frac{25}{9}} = \frac{5}{3}\]
अतः सही विकल्प (b) है।

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