\(eq = {rv\ i1\  + \ r1\ i2\  + \ r2\ i3\  == \ v0, 
		
        \(-r4\)\ i1\  + \ \((r1\  + \ r4\  + \ ra)\)\ i3\  == 0, 
		
        \(-r3\)\ i1\  - \ ra\ i2\  + \ \((r2\  + \ r3\  - ra)\)\ i3\  == 0}; 
    v\  = \ Solve[eq, {i1, i2, i3}]\)

Simplify[eq  /.  iv]

\(v0 = 110; 
rv = 10; 
r1 = 100; 
r2 = 120; 
r3 = 100; 
r4 = 150; 

    ra = 1000; 
{i1, i2, i3} /. iv\)

N[iv, 5]

h = {{-2 b, 0, 0, j}, {0, 0, j, 0}, {0, j, 0, 0}, {j, 0, 0, 2  b}}; 
    Eigenvalues[h]

Eigenvectors[h]

Eigensystem[h]

Det[h]

Inverse[h]

Dot[h, h]