Least-squares fitting of a line or low-degree polynomial to tabulated points

Find the equation of the line for which the sum of the squares of the distances to the points $(3,2)$, $(7,5)$, $(12,9)$, $(-3,-2)$ would be smallest.

Find the equation of a second-order parabola such that the sum of the squares of the vertical distances to it from the points $(-3,4)$, $(-2,2)$, $(-1,1)$, $(0,0)$, $(1,1)$, $(2,2)$, $(3,3)$ would be smallest.