Question 1175989
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It sounds like you want to solve
{{{(matrix(2,3,-4,-4,-2,3,-2,-6))=-5x-2(matrix(2,3,9,-3,-6,8,6,6))}}}

If my assumption is incorrect, and I'm misreading the question, then please let me know. 


Let 
{{{A = (matrix(2,3,-4,-4,-2,3,-2,-6))}}}
and
{{{B = (matrix(2,3,9,-3,-6,8,6,6))}}}


We have the equation
{{{A = -5x-2B}}}


Let's isolate -5x by adding 2B to both sides
{{{A = -5x-2B}}}


{{{A+2B = -5x-2B+2B}}}


{{{A+2B = -5x+0*B}}}


{{{A+2B = -5x+0}}}


{{{A+2B = -5x}}}


{{{-5x = A+2B}}}


Based on the matrix definitions I stated, we know that
{{{A + 2B = (matrix(2,3,-4,-4,-2,3,-2,-6)) + 2*(matrix(2,3,9,-3,-6,8,6,6))}}}


{{{A + 2B = (matrix(2,3,-4,-4,-2,3,-2,-6)) + (matrix(2,3,2*9,2*(-3),2*(-6),2*8,2*6,2*6))}}}


{{{A + 2B = (matrix(2,3,-4,-4,-2,3,-2,-6)) + (matrix(2,3,18,-6,-12,16,12,12))}}}


{{{A + 2B = (matrix(2,3,-4+18,-4+(-6),-2+(-12),3+16,-2+12,-6+12))}}}


{{{A + 2B = (matrix(2,3,14,-10,-14,19,10,6))}}}


So,
{{{-5x = A+2B}}}


{{{-5x = (matrix(2,3,14,-10,-14,19,10,6))}}}


{{{x = (-1/5)*(matrix(2,3,14,-10,-14,19,10,6))}}}


{{{x = -0.2*(matrix(2,3,14,-10,-14,19,10,6))}}}


{{{x = (matrix(2,3,-0.2*14,-0.2*(-10),-0.2*(-14),-0.2*19,-0.2*10,-0.2*6))}}}


{{{x = (matrix(2,3,-2.8, 2, 2.8, -3.8, -2, -1.2))}}}


We see that x is a matrix. Convention usually has uppercase letters as the labels of a matrix. This means it is better to use uppercase X instead of lowercase x.


This matrix has two rows and three columns.
The first row has the numbers: -2.8, 2, 2.8
The second row has the numbers: -3.8, -2, -1.2


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To check this answer, we'll do the following steps<ol><li>Multiply every entry in matrix X by -5. This computes the expression -5X. Let's call this result matrix C.</li><li>Multiply every entry in the matrix B by 2. We'll call this result matrix D.</li><li>Subtract the matrices C and D. The order is C-D. You'll pair up each corresponding entry when doing the subtraction. Let's call this result matrix E.</li></ol>We should have these matrices:
{{{A = (matrix(2,3,-4,-4,-2,3,-2,-6))}}} (note how A = E)


{{{B = (matrix(2,3,9,-3,-6,8,6,6))}}}


{{{C = (matrix(2,3,14,-10,-14,19,10,6))}}}


{{{D = (matrix(2,3,18,-6,-12,16,12,12))}}}


{{{E = (matrix(2,3,-4,-4,-2,3,-2,-6))}}} (note how A = E)


{{{X = (matrix(2,3,-2.8, 2, 2.8, -3.8, -2, -1.2))}}} 


The entire right hand side of -5X-2B becomes matrix E. Since matrix A and matrix E are the same, this shows that A = E and that leads to A = -5X-2B being true as well. This confirms the answer. 


Side notes:
-2.8 = -14/5
-3.8 = -19/5
-1.2 = -6/5
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