यदि \(a_1=4\) और पहले (5) पदों का योग (484) है, तथा (r) धनात्मक पूर्णांक है, तो (r) क्या है?
If \(a_1=4\) and the sum of the first (5) terms is (484), and (r) is a positive integer, what is (r)?
Explanation opens after your attempt
B. (3)
Concept
For (r=3), the terms are (4,12,36,108,324) and the sum is (484). For small options, forming the terms is quick.
Why this answer is correct
The correct answer is B. (3). For (r=3), the terms are (4,12,36,108,324) and the sum is (484). For small options, forming the terms is quick.
Exam Tip
(r=3) पर पद (4,12,36,108,324) हैं और योग (484) है। छोटे विकल्पों में पद बनाकर जांचना तेज होता है।
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