[Persian]

Nguyên văn bởi phantiendat_hv

Bài 4: $\left\{ \begin{array}{l}
\left| {xy - 4} \right| = 8 \\
xy = 2x^2 \\
\end{array} \right
$

$\[\left\{ \begin{array}{l}
\left| {xy - 4} \right| = 8\\
xy = 2{x^2}
\end{array} \right. $ $\Leftrightarrow \left\{ \begin{array}{l}
\left[ \begin{array}{l}
xy = 12\\
xy = - 4
\end{array} \right.\\
2{x^2} = xy
\end{array} \right. $ $\Leftrightarrow \left\{ \begin{array}{l}
xy = 12\\
{x^2} = 6
\end{array} \right. $
$\[ \Leftrightarrow \left[ \begin{array}{l}
\left\{ \begin{array}{l}
x = \sqrt 6 \\
y = 2\sqrt 6
\end{array} \right.\\
\left\{ \begin{array}{l}
x = - \sqrt 6 \\
y = - 2\sqrt 6
\end{array} \right.
\end{array} \right.\] $
[RIGHT][I][B]Nguồn: MathScope.ORG[/B][/I][/RIGHT]