यदि (5) अलग किताबों में से (2) किताबें चुनकर display order में रखनी हों तो सही expression क्या है?
If (2) books are chosen from (5) distinct books and placed in display order what is the correct expression?
Explanation opens after your attempt
B. \(^{5}C_2\times2!\)
Concept
First choose the books and then assign display order. In exams multiply by (r!) when order follows selection.
Why this answer is correct
The correct answer is B. \(^{5}C_2\times2!\). First choose the books and then assign display order. In exams multiply by (r!) when order follows selection.
Exam Tip
पहले किताबें चुनें फिर display order दें। परीक्षा में selection के बाद order हो तो (r!) से गुणा करें।
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