Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If a = \(\frac{2 + \sqrt {3}}{2 - \sqrt {3}}\), b = \(\frac{2 - \sqrt {3}}{2 + \sqrt {3}}\), then

find (a + b)².

Options:

225

196

441

400

Correct Answer:

196

Explanation:

a = \(\frac{2 + \sqrt {3}}{2 - \sqrt {3}}\) × \(\frac{2 + \sqrt {3}}{2+ \sqrt {3}}\) = \(\frac{(2 + \sqrt {3})^2}{1}\) = 7 + 4\(\sqrt {3}\)

Similarly, b = 7 - 4\(\sqrt {3}\)

⇒ a + b = 7 + 4\(\sqrt {3}\) + 7 - 4\(\sqrt {3}\) = 14

⇒ (a + b)² = 196