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

We solve polynomials algebraically in order to determine the roots - where a curve cuts the \(x\)-axis. A root of a polynomial function, \(f(x)\), is a value for \(x\) for which \(f(x) = 0\).