We want to find 2a - 3b as a column vector, we will get:
[tex]2a - 3b = \left[\begin{array}{ccc}-9\\14\end{array}\right][/tex]
So we want to perform a sum (difference actually) of vectors, we have that:
[tex]a = \left[\begin{array}{ccc}3\\4\end{array}\right] \\\\\\b= \left[\begin{array}{ccc}5\\-2\end{array}\right][/tex]
Remember that when we multiply a vector by a scalar, each component gets multiplied by that scalar, so we have:
[tex]2a = \left[\begin{array}{ccc}2*3\\2*4\end{array}\right] = \left[\begin{array}{ccc}6\\8\end{array}\right] \\\\\\3b= \left[\begin{array}{ccc}3*5\\3*-2\end{array}\right] = \left[\begin{array}{ccc}15\\-6\end{array}\right][/tex]
Now we just perform the direct difference:
[tex]2a - 3b = \left[\begin{array}{ccc}6\\8\end{array}\right] - \left[\begin{array}{ccc}15\\-6\end{array}\right] = \left[\begin{array}{ccc}6 - 15\\8 + 6\end{array}\right] = \left[\begin{array}{ccc}-9\\14\end{array}\right][/tex]
If you want to learn more, you can read:
https://brainly.com/question/10435343
