6. For the curve y = 2x 3 11x 2 12x 9, determine (a) the value of x so that dy dx = 0, (b) the value of y so that dy dx = 0. (c) Given that 2x 311x 2 12x 9 = (xA) 2 (Bx C), where A, B, and C are constants. Find the values of A, B, and C. Then sketch the graph of 2x 3 11x 2 12x 9. Plot the critical points on the graph