SOLUTION: Could you please help me solve this system of equations by using A^-1? x+5y+5z=-7 x+4y+5z=-5 x+5y+4z=-5

We form the matrix equation  where

, ,   

So the matrix equation is  or

  A  * X =  B     
 

Do you know how to find the inverse of a matrix?
If not post again asking how.  The inverse of 
matrix A is:



So we left-multiply both sides of the equation by this
inverse matrix, 



Do you know how to multiply matrices?  If not
post again asking how.

Multiply the matrices and get this:





So , , 

Edwin