Quadratics, SMB-013 Factorise the parabola described by the equation `y=-x^2-x+12` and find its vertex. (3 marks) --- 6 WORK AREA LINES (style=lined) --- Show Answers Only `y=(3-x)(x+4)` `text{Vertex}\ = (-1/2,12 1/4)` Show Worked Solution `y` `=-x^2-x+12` `=-(x^2+x-12)` `=-(x+4)(x-3)` `=(3-x)(x+4)` `text{Solutions at}\ \ x=3, -4` `text{Line of symmetry at mid-point of solutions.}` `x=(3+(-4))/2=-1/2` `text{Substitute}\ \ x=-1/2\ \ text{into}\ \ y=-x^2-x+12` `y=-1/4+1/2+12=12 1/4` `:.\ text{Vertex}\ = (-1/2,12 1/4)`