Respuesta :
Very simple. You just use the vectors as normal numbers, and multiply the coordinates with 2 and 4 like this:
2*u = 2* (2,4) = (4,8)
4*w = 4* (-1,3) = (-4,12)
(4,8) - (-4,12) = (8,-4)
So the vector has the coordinates (8,-4)
2*u = 2* (2,4) = (4,8)
4*w = 4* (-1,3) = (-4,12)
(4,8) - (-4,12) = (8,-4)
So the vector has the coordinates (8,-4)
[tex]\bf \begin{cases}
u= (-1,3)\\
w =(2,4)\\
----------\\
\textit{scalar multiplication}\\
2u\implies 2(-1,3)\implies 2\cdot -1,2\cdot 3\\
\qquad -2,6\\
4w\implies 4(2,4)\implies 4\cdot 2,4\cdot 4\\
\qquad 8,16\\
----------\\
2u-4w\\
(-2,6)-(8,16)\implies (-2-8\ ,\ 6-16)
\end{cases}[/tex]