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Question
If `1/(8!) + 1/(7!) = x/(9!)`, than x is equal to ______.
Options
90
81
170
50
MCQ
Fill in the Blanks
Solution
If `1/(8!) + 1/(7!) = x/(9!)`, than x is equal to 81.
Explanation:
`1/(8!) + 1/(7!) = x/(9!)`
∴ `1/(8!) + 8/(8 xx 7!) = x/(9!)`
⇒ `(1 + 8)/(8!) = x/(9!)`
⇒ `9/(8!) = x/(9 xx 8!)`
⇒ x = 81
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Properties of Combinations
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