production of two numbers is 19951 and sum of those two numbers is 280 (x+y=280).Without assigned those numbers find difference between them (x-y=?)

Answer 1

well,

(x+y)^2 - (x-y)^2 = 4xy

So, (x-y)^2 = 280^2 - 4*19951

Answer 2

Where did u get the 4(number 4), when u did 4xy?