Hello, I have a small problem that i am having trouble with,

Find the co-ordinates of the point on the curve y=sqrt(x) which is closest to the point (5/2,0)

I already know a little about the process, I know the formula to find distance from the origin is sqrt(x^2+y^2) and I substitute sqrt(x) for y,

But then I simplify it down and get sqrt(-4x).

If i could have some pointers i would be really greatfull.

Thank you.