Câu 3: \(\overrightarrow{a};\overrightarrow{b}\) cùng phương
=>\(\frac{2016\sqrt{2015}}{4}=\frac{0}{x}\)
=>x=0
=>Chọn B
Câu 2: \(\overrightarrow{c}=\overrightarrow{a}-2\cdot\overrightarrow{b}\)
=>\(\begin{cases}x=-4-2\cdot\left(-3\right)=-4+6=2\\ y=1-2\cdot\left(-2\right)=1+4=5\end{cases}\)
=>Chọn B
Câu 1: A(0;2); B(1;4)
=>\(\overrightarrow{AB}=\left(1-0;4-2\right)=\left(1;2\right)\)
A(0;2); M(x;y)
=>\(\overrightarrow{AM}=\left(x-0;y-2\right)=\left(x;y-2\right)\)
\(\overrightarrow{AM}=-2\cdot\overrightarrow{AB}\)
=>\(\begin{cases}x=-2\cdot1=-2\\ y-2=-2\cdot2=-4\end{cases}\Rightarrow\begin{cases}x=-2\\ y=-2\end{cases}\)
=>M(-2;-2)
=>Chọn A
