Câu hỏi
Viết tọa độ các vecto sau :
\(\begin{array}{l}
\vec a = 2\vec i - 3\vec j & & \vec b = \frac{1}{3}\vec i + 5\vec j & \\
\overrightarrow c = 3\overrightarrow i & & & \overrightarrow d = - 2\overrightarrow j
\end{array}\)
- A \(\begin{array}{l}
\overrightarrow a = \left( {2; - 3} \right) & & \overrightarrow b = \left( {\frac{1}{3};\, - 5} \right)\\
\overrightarrow c = \left( {3;\,\,0} \right) & & \overrightarrow d = \left( {0;\,\,2} \right)
\end{array}\) - B \(\begin{array}{l}
\overrightarrow a = \left( {2; - 3} \right) & & \overrightarrow b = \left( {\frac{1}{3};\,\,\,5} \right)\\
\overrightarrow c = \left( {3;\,\,0} \right) & & \overrightarrow d = \left( {0;\,\,2} \right)
\end{array}\) - C \(\begin{array}{l}
\overrightarrow a = \left( {2; - 3} \right) & & \overrightarrow b = \left( {\frac{1}{3};\,\,\,5} \right)\\
\overrightarrow c = \left( { - 3;\,\,0} \right) & & \overrightarrow d = \left( {0;\,\,2} \right)
\end{array}\) - D \(\begin{array}{l}
\overrightarrow a = \left( {2; - 3} \right) & & \overrightarrow b = \left( {\frac{1}{3};\,\,\,5} \right)\\
\overrightarrow c = \left( {3;\,\,0} \right) & & \overrightarrow d = \left( {0;\, - \,2} \right)
\end{array}\)
Lời giải chi tiết:
Theo định nghĩa ta có: \(\vec u = x\vec i + y\vec j\;\; \Leftrightarrow \vec a = \left( {x;y} \right)\)
\( \Rightarrow \left\{ \begin{array}{l}\vec a = \left( {2; - 3} \right)\\\;\vec b = \left( {\frac{1}{3};5} \right)\\\vec c = \left( {3;0} \right)\\\vec d = \left( {0; - 2} \right)\end{array} \right..\)
