[tex]\bf \qquad \qquad \qquad \textit{discriminant of a quadratic} \\\\\\ y=\stackrel{\stackrel{a}{\downarrow }}{-4}x^2\stackrel{\stackrel{b}{\downarrow }}{+4}x\stackrel{\stackrel{c}{\downarrow }}{-1} ~~~~~~~~ \stackrel{discriminant}{b^2-4ac}= \begin{cases} \boxed{0}&\textit{one solution}~~\checkmark\\ positive&\textit{two solutions}\\ negative&\textit{no solution} \end{cases} \\\\\\ 4^2-4(-4)(-1)\implies 16-16\implies \boxed{0}[/tex]
