KVPY2013MathematicsPermutation and Combination
How many natural numbers n are there such that n !+10 is a perfect square?
Options
- A1
- B2
- C4
- Dinfinitely many
Correct answer
A. 1
Step-by-step solution
If n =1,2,4,5, n !+10 is not a perfect square If n =3, n !+10 is a perfact square If n>5 than exponant of 2 is one so it is not a perfact square.