Đáp án:
Giải thích các bước giải:
\[\begin{array}{l}
\overrightarrow c = x\overrightarrow a + y\overrightarrow b \Leftrightarrow \left\{ \begin{array}{l}
{x_{\overrightarrow c }} = x.{x_{\overrightarrow a }} + y.{x_{\overrightarrow b }}\\
{y_{\overrightarrow c }} = x.{y_{\overrightarrow a }} + y.{y_{\overrightarrow b }}
\end{array} \right.\\
a.\left\{ \begin{array}{l}
2x + y = 5\\
x + 3y = 10
\end{array} \right. \Rightarrow \left\{ \begin{array}{l}
x = 1\\
y = 3
\end{array} \right.\\
b,\left\{ \begin{array}{l}
x + 3y = 7\\
5x - y = 3
\end{array} \right. \Rightarrow \left\{ \begin{array}{l}
x = 1\\
y = 2
\end{array} \right.\\
c.\left\{ \begin{array}{l}
- x + 2y = 4\\
3x + 3y = - 3
\end{array} \right. \Rightarrow \left\{ \begin{array}{l}
x = - 2\\
y = 1
\end{array} \right.
\end{array}\]
