Question

If `1/(8!) + 1/(7!) = x/(9!)`, than x is equal to ______.

विकल्प

• 90

• 81

• 170

• 50

Answer 1

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