यदि \(a_1=8\) और पहले (7) पदों का योग (161) है, तो समान अंतर क्या है?
If \(a_1=8\) and the sum of the first (7) terms is (161), what is the common difference?
Explanation opens after your attempt
B. (5)
Concept
(\frac{7}{2}[2(8)+6d]=161) gives (56+21d=161) and (d=5). In sum questions, substitute (n) and (a) first.
Why this answer is correct
The correct answer is B. (5). (\frac{7}{2}[2(8)+6d]=161) gives (56+21d=161) and (d=5). In sum questions, substitute (n) and (a) first.
Exam Tip
(\frac{7}{2}[2(8)+6d]=161) से (56+21d=161) और (d=5)। योग वाले प्रश्न में पहले (n) और (a) रखें।
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