Quadratics, SMB-012 Factorise `y=x^2-8x+15` (1 mark) --- 2 WORK AREA LINES (style=lined) --- Find the vertex of the parabola with equation `y=x^2-8x+15` (2 marks) --- 4 WORK AREA LINES (style=lined) --- Show Answers Only `y=(x-5)(x-3)` `text{Vertex}\ = (4,-1)` Show Worked Solution i. `y` `=x^2-8x+15` `=(x-5)(x-3)` ii. `text{Solutions at}\ \ x=3,5.` `text{Line of symmetry at mid-point of solutions.}` `x=(3+5)/2=4` `text{Substitute}\ \ x=4\ \ text{into}\ \ y=x^2-8x+15` `y=4^2-8xx4+15=-1` `:.\ text{Vertex}\ = (4,-1)`