गुणोत्तर श्रेढ़ी \(a,ar,ar^2,\ldots\) में \(a_1=9\) और \(a_4=72\) है। धनात्मक (r) क्या होगा?
In the geometric progression \(a,ar,ar^2,\ldots\), \(a_1=9\) and \(a_4=72\). What will be the positive (r)?
Explanation opens after your attempt
A. (2)
Concept
\(a_4=a_1r^3\), so \(72=9r^3\) and \(r^3=8\), hence (r=2). Use the position gap as the exponent.
Why this answer is correct
The correct answer is A. (2). \(a_4=a_1r^3\), so \(72=9r^3\) and \(r^3=8\), hence (r=2). Use the position gap as the exponent.
Exam Tip
\(a_4=a_1r^3\), इसलिए \(72=9r^3\) और \(r^3=8\), अतः (r=2)। पदों की दूरी को घात बनाएं।
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