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Question : If $a=\frac{1}{a - 5}(a>0)$, then the value of $a+\frac{1}{a}$ is:

Option 1: $\sqrt{29}$

Option 2: $–\sqrt{27}$

Option 3: $-\sqrt{29}$

Option 4: $\sqrt{27}$


Team Careers360 13th Jan, 2024
Answer (1)
Team Careers360 20th Jan, 2024

Correct Answer: $\sqrt{29}$


Solution : Given: $a=\frac{1}{a-5}(a>0)$
⇒ $a^{2}-5a=1$
Dividing both sides by $a$ we have,
⇒ $a - 5=\frac{1}{a}$
⇒ $a-\frac{1}{a}=5$
We know that: $(a+\frac{1}{a})^{2}-(a-\frac{1}{a})^{2}=4$
⇒ $(a+\frac{1}{a})^{2}-(5)^{2}=4$
⇒ $(a+\frac{1}{a})^{2}=25+4$
$\therefore(a+\frac{1}{a})=\sqrt{29}$
Hence, the correct answer is $\sqrt{29}$.

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