If a firm doubles its resource inputs and as a result output triples, then the long-run average cost curve must be upward-sloping.

Long-Run Average Cost

The per-unit cost of production in the long-term, where all input factors are variable, indicating economies or diseconomies of scale.

Upward-Sloping

Describes a line on a graph that demonstrates an increase in value as it moves to the right, often used to represent increases in costs or prices.