6. A demand curve can be derived for a good by using the indifference curve–budget constraint apparatus. A point on the demand curve is represented by the tangency of the highest indifference curve to the budget constraint. As price is allowed to fall, the intercept of the budget constraint for the good whose price has fallen shifts outward. A consumer can now choose a larger quantity of the good represented by the tangency of another indifference curve to the new budget constraint. Price falls and the quantity demanded increases. The law of demand is supported once again.