If \(y=7+4\sqrt{3}\), what is the value of \(y+\frac{1}{y}\)?यदि \(y=7+4\sqrt{3}\) है, तो \(y+\frac{1}{y}\) का मान क्या है?
Answer and explanationउत्तर और व्याख्या
Correct answer:सही उत्तर: \(14\)\(14\)
Since \((7+4\sqrt{3})(7-4\sqrt{3})=49-48=1\), we get \(\frac{1}{7+4\sqrt{3}}=7-4\sqrt{3}\). Therefore, \(y+\frac{1}{y}=(7+4\sqrt{3})+(7-4\sqrt{3})=14\). Exam tip: For expressions of the form \(a+b\sqrt{c}\), use the conjugate \(a-b\sqrt{c}\) to rationalise the denominator.क्योंकि \((7+4\sqrt{3})(7-4\sqrt{3})=49-48=1\), इसलिए \(\frac{1}{7+4\sqrt{3}}=7-4\sqrt{3}\)। अतः \(y+\frac{1}{y}=(7+4\sqrt{3})+(7-4\sqrt{3})=14\)। परीक्षा-युक्ति: ऐसे प्रश्नों में हर का परिमेयकरण करने के लिए संयुग्मी \(a-b\) का उपयोग करें।
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