गुणोत्तर श्रेणी में \(a_2=20\) और \(a_5=2500\) है, तो \(a_1\) क्या है?
In a geometric progression, \(a_2=20\) and \(a_5=2500\). What is \(a_1\)?
Explanation opens after your attempt
B. (4)
Concept
From \(\frac{2500}{20}=125=r^3\), (r=5) and \(a_1=20\div5=4\). In exams, find (r) first and then \(a_1\).
Why this answer is correct
The correct answer is B. (4). From \(\frac{2500}{20}=125=r^3\), (r=5) and \(a_1=20\div5=4\). In exams, find (r) first and then \(a_1\).
Exam Tip
\(\frac{2500}{20}=125=r^3\) से (r=5) और \(a_1=20\div5=4\) है। परीक्षा में पहले (r) निकालें फिर \(a_1\)।
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