Question

This assignment is due is half an hour and I'm really lost

Answer 1

Answer:

$3B - 4C = \left[\begin{array}{cc}-8 &-23\\1&-15\end{array}\right]$

Explanation:

Given

$B = \left[\begin{array}{cc}8&-5\\-1&3\end{array}\right]$

$C = \left[\begin{array}{cc}8&2\\-1&6\end{array}\right]$

Required

Determine 3B - 4C

If

$B = \left[\begin{array}{cc}8&-5\\-1&3\end{array}\right]$

Then

$3B = 3 * \left[\begin{array}{cc}8&-5\\-1&3\end{array}\right]$

$3B = \left[\begin{array}{cc}24&-15\\-3&9\end{array}\right]$

Similarly,

If

$C = \left[\begin{array}{cc}8&2\\-1&6\end{array}\right]$

Then

$4C = 4 * \left[\begin{array}{cc}8&2\\-1&6\end{array}\right]$

$4C = \left[\begin{array}{cc}32&8\\-4&24\end{array}\right]$

So:

$3B - 4C = \left[\begin{array}{cc}24&-15\\-3&9\end{array}\right] - \left[\begin{array}{cc}32&8\\-4&24\end{array}\right]$

This gives:

$3B - 4C = \left[\begin{array}{cc}24 - 32 &-15-8\\-3-(-4)&9-24\end{array}\right]$

$3B - 4C = \left[\begin{array}{cc}-8 &-23\\1&-15\end{array}\right]$