Consider the given expression to be a function.
The domain is {x0<=x<=156.25}
so there aren't many values to check.
f(0)=5
f(625/4)=f(156.25)=sqrt(50) = 7.071
and the function is increasing. (Dont ask for a proof)
So we can only have f(x)=6 and f(x)=7
It turns out f(121/4)=6 and f(144)=7
so the only positive integer that yields and integer is 144.

Posted by Jer
on 20090320 13:22:09 