Question

is demand a vertical or horizontal

Answer 1

Demand curve is a downward sloping curve when plotted with prices and quantity demanded. This is because of law of demand that states that with an increase in price, the good become a expensive and quantity demanded decreases. Thus, with a fall in price, quantity increase and vice versa.

A horizontal demand curve is a special case where demand is completely elastic, I.e. if the price changes, the demand reduces to zero. Similarly a vertical demand curve depicts a completely inelastic demand where no matter what the change in price is, quantity demanded remains the same.

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