Question
Download Solution PDFn प्रेक्षणों का माध्य
1, 4, 9, 16 ...., n2 130 है। n का मान क्या है?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFव्याख्या:
माध्य = \(\frac{1+ 4+ 9 ... n^2}{n}\)
⇒ 130 = \(\frac{n(n+1)(2n+1)}{6n}\)
⇒ 780 = 2n2 + 3n + 1
⇒ 2n2 + 3n - 779 =0
⇒ 2n2 + 41n - 38n - 779 = 0
⇒ n(2n + 41) - 19(2n + 41) = 0
⇒ (2n + 41) (n - 19) = 0
⇒ n = 19 ..... ( n = \(-\frac{41}{2}\) संभव नहीं है)
∴ विकल्प (b) सही है।
Last updated on May 30, 2025
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