Chắc là biểu thức vecto?
Gọi \(E\left(x;y\right)\Rightarrow\left\{{}\begin{matrix}\overrightarrow{AE}=\left(x+2;y\right)\\\overrightarrow{BE}=\left(x-5;y+4\right)\\\overrightarrow{AC}=\left(-3;1\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\overrightarrow{AE}+2\overrightarrow{BE}=\left(3x-8;3y+8\right)\\3\overrightarrow{AC}=\left(-9;3\right)\end{matrix}\right.\)
\(\overrightarrow{AE}+2\overrightarrow{BE}=3\overrightarrow{AC}\Leftrightarrow\left\{{}\begin{matrix}3x-8=-9\\3y+8=3\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x=-\frac{1}{3}\\y=-\frac{5}{3}\end{matrix}\right.\) \(\Rightarrow E\left(-\frac{1}{3};-\frac{5}{3}\right)\)