Providedthe quadratic function y = x2 - 4x -21:
i) Write equation in vertex form y = (x -h)2 + k by completing square.
ii) Using the answers in part (a), determine vertex and equation of its axis of symmetry.
iii) Find its zeros (x - intercepts) using any algebraic method you desire.
iv) Illustrating clearly vertex and its zeros, sketch graph of function. Verify this in graphing calculator.