गुणोत्तर श्रेणी में \(a_2=18\) और \(a_5=486\) है तो \(a_1\) क्या है?
In a geometric progression \(a_2=18\) and \(a_5=486\). What is \(a_1\)?
Explanation opens after your attempt
C. (6)
Concept
From \(\frac{486}{18}=27=r^3\), (r=3) and \(a_1=18\div3=6\). In exams find (r) first and then \(a_1\).
Why this answer is correct
The correct answer is C. (6). From \(\frac{486}{18}=27=r^3\), (r=3) and \(a_1=18\div3=6\). In exams find (r) first and then \(a_1\).
Exam Tip
\(\frac{486}{18}=27=r^3\) से (r=3) और \(a_1=18\div3=6\) है। परीक्षा में पहले (r) निकालें फिर \(a_1\)।
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