Question 1159497
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Multiple matrix multiplications are performed in order, left to right:
A*B*C = (A*B)*C<br>
A*B:  (the product of a 1X3 matrix and a 3X3 matrix is a 1X3 matrix)
{{{(matrix(1,3,x,2,1))*(matrix(3,3,2,4,-2,4,1,3,-2,41,3))}}}
= {{{(matrix(1,3,x*2+2*4+1*(-2),x*4+2*1+1*41,x*(-2)+2*3)+1*3))}}}
 = {{{(matrix(1,3,2x+6,4x+43,-2x+9))}}}<br>
(A*B)*C:  (the product of a 1X3 matrix and a 3X1 matrix is a 1X1 matrix)
{{{(matrix(1,3,2x+6,4x+43,-2x+9))*(matrix(3,1,x,-1,3))}}}
= {{{(matrix(1,1,(2x+6)(x)+(4x+43)(-1)+(-2x+9)(3)))}}}
 = {{{(matrix(1,1,2x^2-4x-16))}}}<br>
We need the product of the matrices to be 0:<br>
{{{2x^2-4x-16 = 0}}}
{{{x^2-2x-8 = 0}}}
{{{(x-4)(x+2) = 0}}}
{{{x = 4}}}  OR  {{{x = -2}}}<br>