अनुक्रम \(1,5,11,19,\ldots\) का सामान्य पद क्या है?
What is the general term of the sequence \(1,5,11,19,\ldots\)?
Explanation opens after your attempt
C. \(a_n=n^2+n-1\)
Concept
\(n^2+n-1\) gives (1,5,11,19). In exams, check a quadratic rule when second differences are constant.
Why this answer is correct
The correct answer is C. \(a_n=n^2+n-1\). \(n^2+n-1\) gives (1,5,11,19). In exams, check a quadratic rule when second differences are constant.
Exam Tip
\(n^2+n-1\) से (1,5,11,19) मिलते हैं। परीक्षा में दूसरे अंतर समान हों तो वर्गीय नियम जाँचें।
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