A firm that experiences only constant returns to scale will have a U-shaped long-run average cost curve.

Constant Returns

A condition in production where increasing the amount of inputs results in a proportional increase in outputs.

U-shaped

A graphical representation describing a situation or relationship that initially decreases, reaches a minimum point, and then increases.

Long-run Average Cost

The cost per unit of output when all factors of production, including capital, are variable and optimized for scale.