If the demand curve for product X shifts to the left as the price of product Y increases, then X and Y are complementary goods.

Question

Quizplus · Accepted Answer

Complementary goods are products that are typically used together, such as peanut butter and jelly. If the price of one complementary good increases, the demand for both goods decreases, resulting in a leftward shift of the demand curve for both goods. In this case, as the price of product Y (presumably a complementary good to X) increases, the demand for X decreases, causing a leftward shift in the demand curve for X.

If the Demand Curve for Product X Shifts to the Left