यदि \(r=\sqrt{21}+\sqrt{5}\) और \(s=\sqrt{21}-\sqrt{5}\) हैं, तो (rs) का मान क्या है?
If \(r=\sqrt{21}+\sqrt{5}\) and \(s=\sqrt{21}-\sqrt{5}\), what is the value of (rs)?
Explanation opens after your attempt
A. (16)
Concept
This is conjugate multiplication. Therefore (rs=21-5=16).
Why this answer is correct
The correct answer is A. (16). This is conjugate multiplication. Therefore (rs=21-5=16).
Exam Tip
यह संयुग्मी गुणन है। इसलिए (rs=21-5=16) होगा।
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