2.78 Given a set of linear equations automatically generate the matrix A and vector b and solve \(A x=b\)

Problem: Given \[{\begin {array} [c]{ccc}4x+4y+2z & = & 12\\ 5x+6y+3z & = & 7\\ 9x+7y+10z & = & 9 \end {array}} \]

Automatically convert it to the form \(Ax=b\) and solve

Mathematica

Remove["Global`*"] 
eqs = {4x+3y+2z==12, 
       5x+6y+3z  ==7, 
       9x+7y+10z ==9}; 
 
{b,a} = CoefficientArrays[eqs,{x,y,z}]; 
 
Normal[a]//MatrixForm
 

\[ \left ( {\begin {array}{ccc} 4 & 3 & 2 \\ 5 & 6 & 3 \\ 9 & 7 & 10 \\ \end {array}} \right ) \]

Normal[b]//MatrixForm
 

\[ \{-12,-7,-9\} \]

LinearSolve[a,-b]//N
 

{6.71429,-2.85714,-3.14286}
 

 

Maple

restart; 
eqs:=[4*x+3*y+2*z=12,5*x+6*y+3*z=7,9*x+7*y+10*z=9]; 
A,b := LinearAlgebra:-GenerateMatrix(eqs,[x,y,z]); 
LinearAlgebra:-LinearSolve(A,b)
 

\[ \left [\begin {array}{c} \frac {47}{7} \\ -\frac {20}{7} \\ -\frac {22}{7} \end {array}\right ] \]