1. solve 3x^3-20x^2+33x-14<0
2. Find the formula of this graph
So are the points of interest.
is the solution.
2. I am not sure whether exact formula of the graph can be derived. However, you can find an approximate formula which satisfies some values of the graph http://en.wikipedia.org/wiki/Linear_interpolation
It appears from the graph that f(-2)= 0, f(3)= 0, and f(0)= 3 and there is a minimum at x= -2 so f'(-2)= 0. If that is right and we are allowed to assume this function is cubic, then write it as and then . Put f(-2)= 0, f(3)= 0, f(0)= 3 into the first equation and f'(-2)= 0 into the second to get 4 equations to solve for a, b, c, and d.