Now, given y=x^3 -9x^2+23x-16 on the interval [-3,7] the maximum and minimum values would be the turning points right? also, a stationary point of inflextion is where the grandient is zero, with a positive or negative gradient on both sides right? i am asked to find the EXACT values of the x-coordinates of the points of inflection on the graph of -x^4 + 3x^3 + 5x^2 + 2x + 11 but, there are two maximums and one minimum, not a stationary point of inflection. So, are minimum and maximum values points of inflections? Also, how do i obtain an EXACT value for the x coordinates.