(10) books में से (4) books चुननी हैं लेकिन (2) fixed books साथ में या तो दोनों आएं या दोनों न आएं। Count कौन-सी है?
From (10) books, (4) books are to be selected, and (2) fixed books must either both appear or both not appear. What is the count?
Explanation opens after your attempt
A. \(^{8}C_2+{}^{8}C_4\)
Concept
Case (1): take both fixed books, case (2): take neither. In exams keep cases clear for paired restrictions.
Why this answer is correct
The correct answer is A. \(^{8}C_2+{}^{8}C_4\). Case (1): take both fixed books, case (2): take neither. In exams keep cases clear for paired restrictions.
Exam Tip
Case (1): दोनों fixed लें, case (2): दोनों fixed न लें। परीक्षा में paired restrictions में cases साफ रखें।
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