Calculus Scalar

Question

Find the point on the line y=6x that is closest to the point P = (6,3).

Answer 1

D = (x - 6)² + (6x - 3)²; D' = 2(x - 6) + 2(6x - 3) = 0; 14x - 18 = 0; x = 9/7, y = 6x = 54/7; D'' = 14 > 0 minimum

So, point (9/7, 54/7) closest to point (6, 3)