The coordinates of the turning point and the equation of the line of symmetry can be found by writing the quadratic expression ... graph will cross the \(x\)-axis at \(x = -1\) and \(x = 3\).

The turning point lies on the line of symmetry. Graph of y = ax 2 + bx + c If the graph of the quadratic function \(y = ax^2 + bx + c \) crosses the x-axis, the values of \(x\) at the crossing ...

The equations also show up in calculations ... The two solutions to the quadratic equation will be the axis of symmetry plus or minus an unknown amount, which we’ll call u.