disp('the co-efficient matrix is:')
a=[1 -4 7;0 3 -5;-2 5 -9]
disp(a)
disp('let g,h,k be the constants on RHS')
disp('R3=R3+2*R1')
a(3,:)=a(3,:)+2*a(1,:)
disp(a)
disp('the constants on RHS are:g,h,k+2g')
disp('R3=R3+R2')
a(3,:)=a(3,:)+a(2,:)
disp(a)
disp('the constants on RHS are:g,h,k+2g+h')
disp('for solution to exist')
disp('from R3:k+2g+h=0')