Final answer:
If the cross elasticity of demand for computers with respect to the price of a DVD is negative, then computers and DVDs are complements. A higher price for DVDs will lead to a decrease in the quantity demanded for computers.
Step-by-step explanation:
If the cross elasticity of demand for computers with respect to the price of a DVD is negative, then computers and DVDs are complements. Complement goods have negative cross-price elasticities: if good A is a complement for good B, like coffee and sugar, then a higher price for B will mean a decrease in the quantity demanded of A.