अनुक्रम \(1,3,6,10,15,\ldots\) में कौन सा पद (45) है?
In the sequence \(1,3,6,10,15,\ldots\), which term is (45)?
Explanation opens after your attempt
Correct Answer
B. (9)वाँ(9)th
Concept
This is a triangular sequence with (T_n=\frac{n(n+1)}{2}). Since \(\frac{9\times10}{2}=45\), it is the (9)th term.
Why this answer is correct
The correct answer is B. (9)वाँ / (9)th. This is a triangular sequence with (T_n=\frac{n(n+1)}{2}). Since \(\frac{9\times10}{2}=45\), it is the (9)th term.
Exam Tip
यह त्रिभुजीय अनुक्रम है और (T_n=\frac{n(n+1)}{2}) होता है। \(\frac{9\times10}{2}=45\) इसलिए यह (9)वाँ पद है।
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