Cho \(\vec a = \left( {2;1} \right),\;\vec b = \left( {3;4} \right),\;\vec c = \left( {7;2} \right).\)
a) Tìm tọa độ của vecto \(\vec u = 2\vec a - 3\vec b + \vec c.\)
b) Tìm tọa độ của vecto \(\vec v\)ao cho \(\vec v + \vec a = \vec b - \vec c.\)
c) Tìm các số \(k,\,\,m\) để \(\vec c = k\vec a + m\vec b.\)
A.\(\begin{array}{l}a)\,\,\overrightarrow u = \left( {2;\,\,8} \right)\\b)\,\,\overrightarrow v = \left( { - 6;\,\,1} \right)\\c)\,\,\overrightarrow c = \frac{{22}}{5}\overrightarrow a - \frac{3}{5}\overrightarrow b \end{array}\)
B.\(\begin{array}{l}a)\,\,\overrightarrow u = \left( {2;\, - \,8} \right)\\b)\,\,\overrightarrow v = \left( { - 6;\,\,1} \right)\\c)\,\,\overrightarrow c = \frac{{22}}{5}\overrightarrow a - \frac{3}{5}\overrightarrow b \end{array}\)
C.\(\begin{array}{l}a)\,\,\overrightarrow u = \left( {2;\, - \,8} \right)\\b)\,\,\overrightarrow v = \left( {6;\,\,1} \right)\\c)\,\,\overrightarrow c = \frac{{22}}{5}\overrightarrow a - \frac{3}{5}\overrightarrow b \end{array}\)
D.\(\begin{array}{l}a)\,\,\overrightarrow u = \left( {2;\, - \,8} \right)\\b)\,\,\overrightarrow v = \left( { - 6;\,\,1} \right)\\c)\,\,\overrightarrow c = \frac{{22}}{5}\overrightarrow a + \frac{3}{5}\overrightarrow b \end{array}\)