Here you'll need differential calculus.
The distance between (3,0) and (x, sqrt(2)*x + 4) is given by the distance formula:
distance: sqrt [ (3+x)^2 + (sqrt(2)*x + 4)^2 ]
Differentiate this, and then set the resulting derivative = to 0. Solve for x. Test your results to ensure that the distance d is actually the SMALLEST, given the root(s) x that you've found.
Write the coordinates of this point on the curve as ( x, f(x) ).
