NCERT Class XI Mathematics - Permutations and Combinations - Solutions

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Question : 7
Total: 41
Evaluate
(i) 8 ! (ii) 4 ! – 3 !
Solution:  
3! + 4! = (1 × 2 × 3) + (1 × 2 × 3 × 4) = 6 + 24 = 30 ... (i)
7! = 1 × 2 × 3 × 4 × 5 × 6 × 7 = 5040 ... (ii)
From (i) & (ii), we get 3! + 4! ≠ 7!.
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