X< when =0, the function of f(x)=-(x-3/2) square +9/4 is an increasing function from negative infinity to 0.

0<x< is at 3 places, and the function of the square -9/4 of f(x)=(x-3/2) is a decreasing function from 0 to 3/2, which is a increasing function from 3/2 to 3.

X> when =3, the function of f(x)=(x-3/2) squared -9/4 is an increasing function from 3 to positive infinity.

Therefore, the increasing function interval of f (x) = (x-3) | x | is (-∞, 0U(3/2, +∞).

2. The meaning of the function y is the sum of the distances from the points on the number axis to-1 and 2. We can know that the decreasing interval is (-∞, the increasing interval is-1 is 2, +∞).