किसी समांतर श्रेणी का (n)वाँ पद \(a_n=4n-1\) है। पहले (12) पदों का योग ज्ञात कीजिए।
The (n)th term of an arithmetic progression is \(a_n=4n-1\). Find the sum of the first (12) terms.
Explanation opens after your attempt
B. (300)
Concept
The first term is (3) and the twelfth term is (47), so (S_{12}=\frac{12}{2}(3+47)=300). Use \(a_n\) to find the first and last terms.
Why this answer is correct
The correct answer is B. (300). The first term is (3) and the twelfth term is (47), so (S_{12}=\frac{12}{2}(3+47)=300). Use \(a_n\) to find the first and last terms.
Exam Tip
पहला पद (3) और बारहवाँ पद (47) है, इसलिए (S_{12}=\frac{12}{2}(3+47)=300)। \(a_n\) से पहले और अंतिम पद निकालें।
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