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NCERT Class XI Mathematics - Permutations and Combinations - Solutions

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Question : 9 of 41
Marks: +1, -0
If 16!+17!\frac{1}{6!} + \frac{1}{7!} = x8!\frac{x}{8!} , find x
Solution:  
We have , If 16!+17!\frac{1}{6!} + \frac{1}{7!} = x8!\frac{x}{8!} ⇒ 16!+17×6!\frac{1}{6!} + \frac{1}{7\times 6!} = x8×7×6!\frac{x}{8\times 7\times 6!}
⇒ 1 + 17\frac{1}{7} = x56\frac{x}{56} ⇒ 87\frac{8}{7} = x56\frac{x}{56} ⇒ x = 87\frac{8}{7} × 56 = 64
So, x = 64
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