$Find\ the\ point\ on\ the\ straight\ line\ 2x+3y=6\ which\ is\ closest\ to\ the\ origin?$
Harder would be to write the distance function $\sqrt{x^2+ y^2}= \sqrt{x^2+ (-\frac{2}{3}x+ 2)^2}$ which is minimal only when its square, $x^2+ (-\frac{2}{3}x+ 2)^2$, is minimal, and find where the derivative is 0.