#((1, -2, 8), (1, -2, 6), (2, -4, 19)) cdot ((x), (y), (z)) = ((-4), (-2), (-11))#
#((1, -2, 8), (1-1, -2+2, 6-8), (2-2, -4+4, 19-16)) cdot ((x), (y), (z)) = ((-4), (-2+4), (-11+8))#
#((1, -2, 8), (0, 0, -2), (0, 0, 3)) cdot ((x), (y), (z)) = ((-4), (2), (-3))#
#z = -1# and #x - 2y - 8 = -4 Rightarrow x = 2y + 4#
#((x), (y), (z)) = ((2y + 4), (y), (-1)) = y cdot ((2), (1), (0)) + ((4), (0), (-1)) #