Using the quadratic formula is another method of solving quadratic equations that will not factorise ... The first solution is \(x = \frac{-6 + \sqrt{84}}{2} = 1.58\) (3 sf).

The roots are \(x=-6\) and \(x=4\). The aixs of the symmetry is halfway between these at \(x=-1\). If we multiply out the brackets the coefficient of \(x\) 2 is 1. As this is \(a\textgreater0 ...