Find the point on the line 3x + 2y -3 = 0, which is closest to the point (1, -3).
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Call this point (a,b). Solve line equation for y. Now use the distance formula between the point (1,-3) and (a,b).
Two hints: 1) (a,b) = (a,f(a)) where f(a) is the y-value for x=a
2) The distance formula has a nasty square-root. If you minimize D^2, you also minimize D. So you can drop the square root.
Differentiate and find critical point.