a. Determine the interval(s) where the function is decreasing: f(x)=2x3-3x2-12x+18
b. Find the x-coordinate of the local maximum of f(x)=x3-1.2x2-1.8x
c. Find the x-coordinate of the inflection point of f(x)=x3-2.3x2-1.4x
d. Find the absolute minimum value of the function f(x)=x2-5.6x+1 on the interval [0,2].