एक थिएटर की पहली पंक्ति में (18) सीटें हैं और हर अगली पंक्ति में (2) सीटें अधिक हैं। (20)वीं पंक्ति में कितनी सीटें होंगी?
A theatre has (18) seats in the first row and each next row has (2) more seats. How many seats are in the (20)th row?
Explanation opens after your attempt
B. (56)
Concept
\(a_{20}=18+19\times2=56\). For row number (20), the difference is added (19) times.
Why this answer is correct
The correct answer is B. (56). \(a_{20}=18+19\times2=56\). For row number (20), the difference is added (19) times.
Exam Tip
\(a_{20}=18+19\times2=56\)। पंक्ति संख्या (20) होने पर अंतर (19) बार जुड़ता है।
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