यदि \(x=2+\sqrt{7}\), तो \(x+\frac{1}{x}\) का मान क्या है?
If \(x=2+\sqrt{7}\), what is the value of \(x+\frac{1}{x}\)?
Explanation opens after your attempt
Correct Answer
A. \(2\sqrt{7}\)
Concept
\(\frac{1}{2+\sqrt{7}}\) equals \(\frac{2-\sqrt{7}}{-3}=\frac{\sqrt{7}-2}{3}\). So \(x+\frac{1}{x}=2+\sqrt{7}+\frac{\sqrt{7}-2}{3}=\frac{4+4\sqrt{7}}{3}\).
Why this answer is correct
The correct answer is A. \(2\sqrt{7}\). \(\frac{1}{2+\sqrt{7}}\) equals \(\frac{2-\sqrt{7}}{-3}=\frac{\sqrt{7}-2}{3}\). So \(x+\frac{1}{x}=2+\sqrt{7}+\frac{\sqrt{7}-2}{3}=\frac{4+4\sqrt{7}}{3}\).
Exam Tip
\(\frac{1}{2+\sqrt{7}}=\frac{\sqrt{7}-2}{3}\) नहीं बल्कि हर (4-7=-3) से मान \(\frac{2-\sqrt{7}}{3}\) है इसलिए सीधा विकल्प नहीं बनेगा। सही सरलीकरण जांचे बिना उत्तर न चुनें।
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