How to do it? I hv no idea. Thanks.

SECTION B (22 marks) x - 5 12. (a) If the equation -x2 + kx - 21 = 0 has two distinct real roots, find the y - -x? + kx- 21 range of values of k. (3 marks) (b) The figure shows the graph of y = -x2 + kx - 21, where k > 0. It cuts the x-axis at (a, 0) and (B, 0). The axis of symmetry is x = 5. Find the values of k, a and B. X (ii) Solve x2 - kx + 21 50. (iii) Hence, or otherwise, solve (1 - 2y)2 + 2ky S k - 21. (7 marks)