A firm's ___________________ are costs that increase as quantity produced increases. These costs often show _______________________ by increasing at an increasing rate. fixed costs; technological changes variable costs; constant returns to scale fixed costs; opportunity costs variable costs; diminishing marginal returns A firm's ___________________ are costs that are incurred even if there is no output. In the short run, these costs ___________________ as production increases. variable costs; do not change fixed costs; increase fixed costs; do not change variable costs; increase