Question

`x+y=100`. `x` is a square number. `y` is a prime number. What is `x` and `y`?

Answer 1

x = 81 and y = 19..

Explanation:

y is prime. So, y is an odd integer. And so, x = 100 -y = odd integer.

Therefore, it is square of an odd integer n that is < sqrt 100 = 10.

So, n= 3, 5 7 or 9...

Only `100-9^2=19` is prime.

Thus, `x = 9^2=81 and y = 19`..