Exercício Resolvido de Equações do 2.º Grau
b)
\( \displaystyle x^{2}-5x+4=0 \)
Calculando Δ
\[ \bbox[#99CCFF,10px]
{\Delta =b^{2}-4ac}
\]
\[
\begin{align}
& \Delta =(-5)^{2}-4.1.4\\
& \Delta =25-16\\
& \Delta=9
\end{align}
\]
Cálculo das raízes
\[ \bbox[#99CCFF,10px]
{x_{1,2}=\frac{-b\pm \sqrt{\Delta \;}}{2a}}
\]
\[
\begin{align}
& x_{1,2}=\frac{-(-5)\pm\sqrt{9\;}}{2.1}\\
& x_{1,2}=\frac{5\pm3}{2}\\
& x_{1}=\frac{5+3}{2}=\frac{8}{2}=4\\
& x_{2}=\frac{5-3}{2}=\frac{2}{2}=1
\end{align}
\]
\[ \bbox[#FFCCCC,10px]
{V=\{4,1\}}
\]