u1 = 3x1 + x2, u2 = 6x1 + 2x2, and u3 = 3x1 x2. All three of these have M RS = 3 always. he first two have monotonic preferences: the consumer likes more stuff to less, so higher up indifference curves are further from the origin. The third one has non-monotonic preferences: the consumer likes less stuff over more, so higher up indifference curves are the ones closer to the origin