(c) This part of the question concerns the quadratic function y = x2 - 3x -4. (i) Write the quadratic expression x2 - 3x - 4 in completed-square form, showing your working. best (ii) Use the completed-square form from part (c) (i) to solve the equation x-3x -4= 0. tus sled 9atuon 2:paste was a (iii) Use the completed-square form from part (c) (i) to write down the coordinates of the vertex of the parabola y = x2 - 3x-4. (iv) Provide a sketch of the graph of the parabola y = x2 - 3x -4 If you intend to go on to study more mathematics, then you are advised to sketch by hand for the practice. Whichever method you choose, you should refer to the graph-sketching strategy box in Subsection 2.4 of Unit 10 for information on how to sketch and label a graph correctly