[tex]\bf 5n^2+6n+7=n^2-4n\implies 5n^2+6n+7-n^2+4n=0
\\\\\\
4n^2+10n+7=0\\\\
-------------------------------\\\\
\begin{array}{llccll}
&{{ 4}}x^2&{{ +10}}x&{{ +7}}\\
&\uparrow &\uparrow &\uparrow \\
&a&b&c
\end{array}
\\\\\\
discriminant\implies b^2-4ac=
\begin{cases}
0&\textit{one solution}\\
positive&\textit{two solutions}\\
negative&\textit{no solution}
\end{cases}[/tex]
if you get a positive value, that means 2 real solutions
if you get 0, means 1 real solution only
if you get a negative value, is an imaginary root solution, same as saying no solution.
