Medium MCQ +4 / -1 PYQ · JEE Mains 2021

The value of $$4 + {1 \over {5 + {1 \over {4 + {1 \over {5 + {1 \over {4 + ......\infty }}}}}}}}$$ is :

  1. A 2 + ${2 \over 5}\sqrt {30}$ Correct answer
  2. B 2 + ${4 \over {\sqrt 5 }}\sqrt {30}$
  3. C 5 + ${2 \over 5}\sqrt {30}$
  4. D 4 + ${4 \over {\sqrt 5 }}\sqrt {30}$

Solution

$y = 4 + {1 \over {5 + {1 \over y}}}$<br><br>$\Rightarrow y = 4 + {y \over {5y + 1}}$<br><br>$\Rightarrow 5{y^2} - 20y - 4 = 0$<br><br>$\Rightarrow y = {{20 \pm \sqrt {400 + 80} } \over {10}}$<br><br>$\Rightarrow y = {{20 \pm 4\sqrt {30} } \over {10}},y &gt; 0$<br><br>$\therefore$ $y = {{10 + 2\sqrt {30} } \over 5}$

About this question

Subject: Mathematics · Chapter: Complex Numbers and Quadratic Equations · Topic: Complex Numbers and Argand Plane

This question is part of PrepWiser's free JEE Main question bank. 223 more solved questions on Complex Numbers and Quadratic Equations are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →