To find the turning points we need to find when the differential of the equations with respect to x is equal to 0. (dy/dx = 3x2 - 12 = 0) From this we find that the turning points happen when x = 2, x = -2 Sub this back into the equation of f(x) and we get that the coordinates of the turning points are (2, -10) and (-2, 22) Now to find the nature of these turning points we need to find the values of the second defferential of f(x) (d2y/dx2 = 6x) So at the two turning points the second differentials are equal to 12 and -12 respectively. Therefore the point (2, -10) is a minimum because 12 is more than 0 and the point (-2, 22) is a maximum because -12 is less than 0.