#NEWLINE# def test_solve_lin_sys_3x4_none( ) : #NEWLINE# #INDENT# ( domain , x1 , x2 , x3 , x4 ) = ring ( 'x1,x2,x3,x4' , QQ ) #NEWLINE# eqs = [ ( ( ( ( ( 2 * x1 ) + x2 ) + ( 7 * x3 ) ) - ( 7 * x4 ) ) - 2 ) , ( ( ( ( ( ( - 3 ) * x1 ) + ( 4 * x2 ) ) - ( 5 * x3 ) ) - ( 6 * x4 ) ) - 3 ) , ( ( ( ( x1 + x2 ) + ( 4 * x3 ) ) - ( 5 * x3 ) ) - 2 ) ] #NEWLINE# assert ( solve_lin_sys ( eqs , domain ) == None )