Identify the interval where y = x3 + 3x2 - 2x + 4 is decreasing.

Please be certain to use the symbol "^" to denote exponentiation.  Your function y should be written as

y = x^3 + 3x2 - 2x + 4.

Principle:  if the derivative of a function is negative on a certain x-interval, the function is decreasing on that interval.      Thus, you must differentiate the given function:  find dy/dx.  Set this dy/dx = to 0 and solve the resulting equation for x.  Set up intervals on the # line based upon your solutions.
For example, if x=-1 and x=2, then set up 3 intervals:  (-infinity,-1), (-1,2), and (2, infinity).  Looking at each interval separately, identify the interval or intervals on which the derivative dy/dx is negative.  

This is a critically important skill in calculus and well worth the time and effort required to learn it.

Istg idk..if there all the same length there all the same number but use google