Description of Bottleneck
When using the quadratic formula in the form x=\frac{1}{2} (-p \pm \sqrt{p^2-4q)
students don’t check whether the the quadratic equation to be solved is in the form
x^2 + p x + q = 0,
i.e. that the x^2-coefficient is equal to unity.
That is to say, students don't check whether the prerequisites for the applicability of this formula apply.
This bottleneck is a special case of Scope of formula.
