a + 3b = (-2, 3, 1) + 3*(4, -1, 2a + 3b = (-2, 3, 1) + (12, -3, 6a + 3b = (-2+12, 3-3, 1+6a + 3b = (10, 0, 7)
a + 3b = (-2, 3, 1) + 3*(4, -1, 2
a + 3b = (-2, 3, 1) + (12, -3, 6
a + 3b = (-2+12, 3-3, 1+6
a + 3b = (10, 0, 7)