यदि \(x^2+5x+r=0\) की जड़ें \(\alpha,\beta\) हैं और \(\alpha^2\beta+\alpha\beta^2=-20\), तो (r) क्या है?
If \(\alpha,\beta\) are roots of \(x^2+5x+r=0\) and \(\alpha^2\beta+\alpha\beta^2=-20\), what is (r)?
Explanation opens after your attempt
Correct Answer
A. (4)
Concept
We use (\alpha-2\beta+\alpha\beta-2=\alpha\beta\(\alpha+\beta\)). Here \(\alpha+\beta=-5\), so (r(-5)=-20) and (r=4).
Why this answer is correct
The correct answer is A. (4). We use (\alpha-2\beta+\alpha\beta-2=\alpha\beta\(\alpha+\beta\)). Here \(\alpha+\beta=-5\), so (r(-5)=-20) and (r=4).
Exam Tip
(\alpha-2\beta+\alpha\beta-2=\alpha\beta\(\alpha+\beta\)) होता है। यहाँ \(\alpha+\beta=-5\), इसलिए (r(-5)=-20) और (r=4)।
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